SANAA, Yemen » The calm inside the mosque quickly turned to mayhem as the first victim of a deadly attack on a protest march was brought in on a stretcher. The young man grasped at his abdomen with bloodied hands.

Soon there were dozens of gunshot victims, clutching wounds as they were rushed into the room designed for prayer and reflection, but now functioning as a field hospital for protesters gunned down by their government.

"What are the reasons to kill people? You can’t justify this," said Ghada Qassim, a doctor, overwhelmed by the scene before her. "They have no weapons. It is a disaster."

Nine months ago, when protesters took to the streets in large numbers, demanding the ouster of their autocratic president, Ali Abdullah Saleh, volunteers transformed this mosque into a field clinic, a theater for performing emergency surgery or simply treating those overcome by tear gas.

Saleh’s forces and the bands of plainclothes thugs who support them have repeatedly, over those many months of protest, opened fire with live rounds. Sometimes the wounds are from a sniper’s bullet, other times indiscriminate fire from a Kalashnikov, or perhaps shrapnel from a mortar round. Sometimes it is protesters, seeking to make a point, walking right into open fire.

But always, the mosque fills with the wounded, and always, the volunteers — there are around 300 of them — get down to work.

"We are here so we can do something humanitarian," said Suheib al-Dambani, a 28-year-old paramedic sitting in the back of an ambulance borrowed from the nearby Science and Technology Hospital.

This was another typical day for a country spiraling from blood-soaked crisis to blood-soaked crisis. The protesters will not leave the streets. The president refuses to leave power, the bullets keep flying and the mosque keeps filling with patients. The number of wounded escalated when urban warfare actually broke out in September between government forces and a division of the military that had defected.

When the first gunshots on Tuesday cracked in the streets, al-Dambani jumped into the minivan that acts as an ambulance and sped off.

"We feel very sorry in our hearts about the patients here," said Dr. Mohammed Qubati, the head of the makeshift hospital who during busy weeks has been able to go home for only a few hours. Other days he sleeps alongside other volunteers on the blanket-strewn second floor of the mosque.

"I have seen people with half a body, half a head," he said. "What can we do? We cry."

Two marches had set out on a recent day, departing from the center of the protest, a nearly 2-mile stretch of tents in front of Sanaa University. One group headed into Al Qa’a, a residential neighborhood that was busy with armed pro-government thugs who quickly opened fire with live ammunition. Protesters said Central Security Forces, elite military units, fired tear gas.

Four demonstrators died, a number that to the calloused veterans of this showdown was relatively small. In March, snipers killed 50 demonstrators.

The field hospital was established in an ad hoc manner in March, during the early days of the protest movement, after forces supporting Saleh, who has ruled for 33 years, started attacking protesters.

It was selected because it was centrally located and provided a large sanctuary for the wounded. The imams of the mosque consented, and since then outside hospitals, businessmen, nongovernmental organizations and even the World Health Organization have donated supplies and money. There is a pharmacy where sick protesters can go for free medicine and patients can even return for free follow-up treatment.

The medical staff started wearing scrubs with the logo "Field Hospital Sana’a" in English and Arabic.

"We are helping civilians," said Ibrahim Dabwan, a volunteer nurse. "We will help any civilians, pro-government, antigovernment. This is our duty."

In its early days, the field hospital was much less organized; doctors would trip over the wounded laid out on the stone floor. But the government’s continued reliance on lethal force has given the staff practice, and so the doctors and nurses move more easily around the small space now, practiced in the chaotic choreography of battlefield medicine.

"The most important thing is to be in the field of the injury — immediate care saves lives," said Tarek Noman, a Western-educated doctor who conducts triage on the patients, to determine who needs to be treated first.

Early one morning, before the bloodletting began, a janitor dressed in green calmly swept the stone floor while a handful of doctors organized their supplies next to rows of about 20 stretchers.

A group of women sat in a corner of the mosque preparing gauze. Two ambulances sat parked outside the gates of the mosque, which are carefully guarded to try to assure that only patients, medical staff members and journalists can enter.

When a wounded woman arrived later, there was a moment of pandemonium as the male volunteers had to call for help from female nurses, who came running in their black abayas. In this conservative society, the women have to be treated separately from the men.

Outside, Noman paced near the main gate, staring at the bodies of two protesters.

"They shouldn’t have transferred those two other guys to the hospital," he said, frustrated over the use of the ambulances for victims with little chance of survival.

"I knew they were going to die," Noman said. "They were shot in the head."

A young man who was only coughing from tear gas was not allowed into the main room. It had started to get too crowded with gunshot victims.

© 2011 The New York Times Company