TUCSON, Ariz. » The moment that Tony Compagno stepped off his fire engine, frantic people spattered with blood began running up to direct him to gunshot victims. Among the wounded was Rep. Gabrielle Giffords, who had been shot in the head. Compagno was one of the first paramedics to reach the scene of the shooting rampage at a shopping center in Tucson last Saturday.

"Lots of people were laying on the ground," said Compagno, from Fire Station 30 the in Northwest Fire/Rescue District of Tucson. "The congresswoman, I could tell that she was still alive. People were giving a little girl CPR. My mind went away. I started counting, and then I thought, ‘What am I counting, injured or dead?"’

There were 19 victims. Compagno’s job was triage: to assess the severity of injuries and label victims so that ambulance crews would know whom to tend to first. He realized instantly that there was no time to write labels. Ambulances and fire engines were roaring up.

The victims, constituents and others who had lined up to talk to Giffords, had dropped where they stood, forming a row 20 or 30 feet long. Compagno could see quickly that five were dead, seven were "immediates," needing help right away, and the rest could wait.

The child receiving CPR was not responding, but Compagno was not about to write her off.

"The little girl, I counted her as an immediate," he said.

Instead of using labels, he simply directed each rescue team to a victim.

The goal was to stabilize them and get them to the hospital as quickly as possible, because people with severe gunshot wounds need trauma surgeons.

The first two patients were ready to go even before the helicopters landed: Nine-year-old Christina-Taylor Green, who had been receiving CPR, and Giffords were loaded into ambulances.

Ten patients were sent to the trauma center at the University of Arizona medical center. The first to arrive was Christina — still getting CPR, still not responding.

By normal standards, a gunshot victim who is unresponsive after 15 minutes of CPR has almost no hope of surviving and can be declared dead. Christina had already received 20 or 25 minutes, according to a report radioed in.

"This was a 9-year-old girl," said Dr. Randall S. Friese, 46, a trauma surgeon. "Even though she had CPR beyond our guidelines, I decided to be aggressive."

Friese said he could not be certain the radio report was correct. But he could not afford the minutes it would take to verify it.

"You decide, and you do," he said. "It’s a personal decision, and I decided to be aggressive, just because she was 9."

He tried a desperate last-ditch maneuver. Within about two minutes, he had cut open her chest, inserted a tube to fill her heart with blood and massaged the heart with his hand to try to start it beating again.

"I had her heart in my hand," Friese said. "We filled it with blood. It still didn’t want to beat. So, it was over. We’re finished."

At that moment, a resident stepped in to tell him a second patient had arrived, assigned to Trauma Room 5: Giffords. It was the first time Friese had heard that she was among the victims.

He told the resident assisting him to fill Christina’s heart and try once more to make it start beating again.

By the time he reached Room 5, the resident had tried, and failed. Christina was gone.

The team in Room 5 had already begun assessing Giffords when Friese arrived.

"I walked in and held her left hand, held it in both of my hands, and I thought to myself, ‘I need to communicate with her,"’ he said. "I was uncertain if she would hear me, that she would process my words. It turned out later that she probably did. That was my reward. I leaned in close to her, and I said, ‘Giffords, you are in a hospital. We are going to take care of you."’

He expected no response. Next, he asked her to squeeze his hand. She did. A few moments later he asked her again, and again she complied. It was cause for hope. But when he tried the same thing with her right hand, there was no response.

Because a brain injury can suddenly impair a person’s ability to breathe, Friese had a breathing tube inserted into her throat. Then he ordered a chest X-ray and a CT scan of her brain.

Dr. Martin E. Weinand, a neurosurgeon, was ready to operate, but Friese thought that the chief of neurosurgery, Dr. G. Michael Lemole Jr., who was supposed to have the day off, should also be involved.

"I called Lemole," Friese said. "That would be a special thing for her. I wouldn’t have done that if it were a regular patient, because one neurosurgeon could do the operation. That to my mind was a political thing, and I wanted another neurosurgeon, particularly the chief neurosurgeon. I felt like I was doing a courtesy to the chief of neurosurgery letting him know the political aspect of what was going on."

Giffords needed surgery immediately. She had skull fractures, dead brain tissue that had to be removed and increasing pressure from swelling that could further damage her brain as it expanded and pressed against her skull. In addition, her eye sockets had fractures.

Lemole and Weinand studied the CT scans, tracked the path of the bullet and decided where to cut. The bullet had passed through her skull. Fortunately, it had not severed arteries or veins. The surgeons plucked out bits of broken skull and dead tissue, and removed part of her skull — less than half on one side — to avoid pressure from swelling. Also to relieve pressure, they expanded the opening that the bullet had made in the dura, the membrane covering the brain. The skull bone, fractured by the bullet, came off in pieces, which are being kept in a freezer and will be put back during reconstructive surgery, probably months away.

A bullet hits the skull like a meteor, Lemole said. Both start to break up, and shards of bone and metal can be driven into the brain.

"The old thinking was to chase after them and pull them out to reduce the chances of infection," he said. "But we learned from the military that it can be worse to chase them" than to leave them there.

Digging around in the brain can damage it further. In any case, he said, the heat of the bullet may have sterilized the embedded fragments.

"We certainly will watch for infection," he said, adding that the greatest risk would be in the first two months.

As Bill Hileman ended his Saturday morning workout, he saw a message on his cell phone from his wife’s number. But the voice belonged to somebody else.

"Bill, this is Nancy. I am with your wife. She was in an accident along with Christina Green," the woman’s voice said, with urgency but not quite panic. "She asked me to call you and let you know that they will be taken to UMC hospital. And if you could, please notify the Greens that Christina will also be taken to the hospital. UMC hospital."

She did not hang up right away and a garbled commotion went on for several seconds. Then, impossible to identify, a high-pitched voice pleaded for help.

Hileman had taken Christina, the daughter of a neighbor, to meet Giffords.

They must have had a fender bender, Hileman assumed. How serious could it be if his wife was aware enough to instruct a stranger to dial his number and urge him to call Christina’s parents? He rushed to the hospital.

He walked through the glass doors into the emergency room lobby just after 11 a.m., noticing people clustered around a television.

"I’m told Suzi Hileman is here," he said to the woman at the front desk.

But the hospital had not identified all the victims. Nobody could tell him anything about his wife.

Shots fired, several dead, the news said. This was not a car accident.

He knew that Safeway. He was certain it was where his wife had taken Christina to see Giffords — the event had been on her calendar for weeks.

"I’m frantic at this point," Hileman said. "I am just jumping up and down, and I can’t get an answer."

A woman who seemed to be in authority grabbed his wrist. She assured him she would find out what was happening. He still did not know if his wife was alive.

By 11:45, Christina’s mother, Roxanna Green, arrived. Her father, John, came sometime later. The moment she identified herself, officials ushered her into a private room.

As Hileman watched this, he said, images of his wife bleeding crowded his mind, and he paced around the emergency room waiting room. Dozens more people began coming in. There were plenty of seats, but few sat down.

Furiously, the people in the room sent and received text messages. They spoke in hushed tones of fear. They exchanged somber, silent glances, aware that their fate was already somehow tied together, but each in a private shroud of misery. In the back corner, a young woman sobbed inconsolably. Her cries, Hileman recalled, were often the loudest sound in the room. He later learned she was Kelly O’Brien, the fiancee of Gabriel Zimmerman, an aide to Giffords, who was killed.

Others gathered with families, but Hileman was alone, still uncertain of his wife’s fate. A social worker from the hospital approached and took his hand. She offered a prayer. The words almost did not matter.

"I am not a religious man," he said. "But at that moment it was the right thing for Suzi."

Then, words flashed across the television screen: Gabby Giffords dead.

The panic spread with a vicious wave. It somehow silenced the room, by then crowded with friends, local leaders and onlookers. It would be nearly an hour before they knew the report was wrong.

By then, hospital officials had ushered the family members of the victims into a private area in the cafeteria. Again, Hileman stood alone.

The Greens came into the room just minutes later. With one look at John Green’s face, red with grief, Hileman knew what had happened to their daughter. A bear of a man, Green "looked like John Wayne collapsing," Hileman said.

"My whole world changed," Hileman said. "My whole world changed on the spot."

A priest had just performed last rites for Christina.

Dr. Peter Rhee, 49, the director of the trauma center at the hospital, was out running, listening to rap music, when a text message landed on his cell phone: 10 patients, multiple gunshot wounds, on the way to the hospital. University Medical Center is the only Level 1 trauma center in southern Arizona, meaning the only one that is accredited, with trauma specialists and operating rooms available around the clock to treat severe injuries.

Standing by the roadside, Rhee called in. Several trauma surgeons were already at the hospital, along with two groups of residents. Anesthesiologists and surgeons from other specialties were volunteering to pitch in. Since it was a Saturday, operating rooms were free.

"Much fortune occurred out of luck," he said. "It was a sunny day, a Saturday, there was no rain or snow, it wasn’t 4 a.m. If it had been a Tuesday at 4 a.m., we would have had one surgeon there."

Satisfied that things were under control, Rhee ran the three miles back home, showered and headed to the hospital.

By the time he arrived there, a stream of ambulances was coming in. A trauma surgeon waited in the ambulance bay to assess patients and assign them to rooms. Teams of doctors and nurses had quickly assembled in each of the center’s seven trauma rooms. Unidentified patients were given "trauma names"– like Agave, Bubble, Cactus, Deer, Egg or Falcon — for medical record-keeping, until their real names could be found.

"I am running the mass casualty, making personnel assignments," Rhee said. "Somebody has to be in charge. I’m checking on the congresswoman in the operating room, looking at her brain. It looks viable to me. I’m making sure the anesthesiologist has blood, and the neurosurgeons have what they need."

The new patients had a daunting array of injuries. Suzi Hileman came by helicopter, minutes behind Christina and Giffords. With gunshot wounds to her abdomen, chest and thigh, Hileman was one of the most vulnerable patients. Within 30 seconds of looking at her, Dr. Bellal Joseph, another trauma surgeon, knew she should go into the operating room.

Hileman was talking — frantically, distractedly, but speaking in a full voice. That meant her airways were clear, a good sign.

Joseph ignored what she was saying so he could stay focused. But he knew Hileman was in shock and petrified.

Hileman does not remember this. She told her husband her last memory was being in a helicopter, feeling humiliated when doctors began removing her clothes.

"The first thing I say to people is always the same," Joseph said. "You are in the hospital. You are going to be fine. You have lots of people doing lots of things for you. This is normal; this is what we do. This is something we know."

At least four more shooting victims were coming in, and it was unclear exactly what they would need. But the more quickly Hileman’s surgery could begin, the more quickly the trauma room could be cleared and cleaned for the next patient.

They placed intravenous lines in her arms and gave her a chest X-ray. There was no sign that any bullets remained in her body. An ultrasound showed no blood gathering around her heart, indicating no serious damage.

In the operating room the purpose was clear.

"All we are trying to do is control the bleeding," Joseph said. "We have to control the shock and basically stop her from dying."

As he made a long incision down Hileman’s stomach, Joseph quickly saw that there was not much internal bleeding.

"That already, your heart rate goes from 130 to about 100," he said. "That’s the thing about trauma; you never know what you are going to get dealt."

Within moments, Joseph made a small incision to examine Hileman’s heart. There were no signs of damage. But there were six bullet holes in her chest, abdomen and legs. He followed the possible trajectories, making sure that he was not missing any damage. He ran his fingers down her intestines, making sure that there were no holes that could potentially cause bleeding or infection.

"I have held every piece of her organs in my own hands," he said. "Her heart was in my hand, her spleen was is in my hand. Her liver was in my hand. There is no better scan that that."

Hours later, Bill Hileman would see his wife for the first time, connected to a tangle of tubes. Hours after that, she would begin calling out for Christina.

Rhee described additional patients but could not name them because they had not given permission.

Patient 4 was shot in the leg and had a cheek and neck wound that Rhee described as "scary." But a CT scan revealed that the facial injury was not so bad, while the bullet to the leg had severed a major vein.

"I was taking care of Patient No. 5," Rhee said. "It looked scary, like he would need the biggest surgery of all."

A huge swelling near the man’s collarbone made it look as if a major artery had been damaged, an injury that would require an exceedingly difficult operation — one that Rhee said he loved to do. As it turned out, the artery was intact, but the patient’s neck and spinal cord were full of bone fragments, and he was lucky not to be paralyzed. In addition, he needed vascular surgery for another bullet wound, one that put him at risk of losing his leg.

Patient 6 was shot in the chest and leg, and needed transfusions.

"He kept bleeding," Rhee said. "I’m wondering if I have to take him to the operating room. But I know that if we can keep his blood pressure a little lower than usual, the bleeding could stop on its own."

He kept his eye on Patient 6, while Patient 5 went to the operating room.

While patients were in surgery, Rhee called a quick huddle of all the doctors still in the trauma center, and they reviewed the list of patients, with each doctor calling out additional information for all the others to hear.

More patients were rolled in. One was shot in the ankle, and needed an orthopedic surgeon.

Another was "initially scary," Rhee said. "She had two holes in her chest, she was shot in her wrist, and when we examined her we could feel a bullet in her back."

The bullet had grazed one breast, entered the other and somehow swung around into her back, possibly hitting her intestines along the way. She needed laparoscopic surgery to find out if her intestines had been damaged; it turned out they had not.

"Relatively, we were lucky that day," Rhee said

Within three hours, every patient was on the way to a hospital bed. The immediate trauma was over. Now, it was Rhee’s task to identify the patients’ families and tell them what happened during surgery.

He walked into the conference rooms in the cafeteria area and pulled aside family groups one at a time. For some patients, there were five people keeping vigil; others awaited news alone.

He began with basic questions to make sure the identity was correct. What is your family member’s name? What does he look like? How old is he?

"We have to be absolutely sure which patient is which, because a lot of patients can’t tell you their names," Rhee said. "When you think you are telling them a particular piece of information, you can tell them something completely wrong. Sometimes a family member can come here thinking that they were shot, when they were actually at a movie or something else."

Rhee made his way down the list quickly. This time, it was simpler, the patients he was talking about now were expected to do well.

"This time it was fairly good news," Rhee said. As he finished the list, he noticed one more family sitting on the benches.

Who are you? Rhee asked. They replied that they were the family of Gabe Zimmerman.

Rhee looked down his list.

"I don’t have this patient here, so that must be lucky for you," he recalled telling them. "I think if I had you on my list, that would have meant you were shot and injured."

"It didn’t dawn on me that they could have been killed in the field, and that’s indeed what happened," Rhee said, who was once a Navy surgeon. "I gave them a false sense of hope at that stage, before they got the real news."

Roughly an hour passed before the family knew what really happened.

Zimmerman, an aide to Giffords, had been pronounced dead at the scene.

Friese does not remember seeing any of the patients come through the doors of the trauma center last Saturday — except for Christina.

Five days after the girl’s death, his secretary told him he was invited to Christina’s funeral. He did not ask from whom the invitation came. Was it from the family? Or did the nurses planning to share a bus to join the thousands of mourners seek him out? It did not matter. Without hesitating, he decided he would go.

There was no time for Friese to meet Roxanna and John Green on Saturday. He was too busy attending to other patients, so it fell to a pediatric specialist to tell them the outcome. And he did not meet them Thursday either.

"I’m very glad that I didn’t meet her parents," he said. "I think I would have had trouble. I would have had emotional …"

His voice trailed off.

"I would have embarrassed myself," he said. He closed his eyes for just a moment and sighed once more. "I usually don’t get upset."

He added, "I don’t know why, it’s just tough."

When he showed up at the funeral in his blue scrubs and his white surgeon’s jacket, police officers helped him move through the overflow crowd waiting outside the church. He was ushered right in.

It was the first time he had ever attended a patient’s funeral.

© 2011 The New York Times Company