LOS ANGELES >> A man stabbed and critically injured a doctor and two nurses inside a Southern California hospital emergency ward on Friday and remained inside as police tried to talk him into surrendering, authorities said.

The man walked into Encino Hospital Medical Center in the San Fernando Valley shortly before 4 p.m., Los Angeles police Officer Drake Madison said.

Fire officials said three victims were taken to a trauma center in critical condition, although later reports said they were stable.

The man remained inside the hospital more than two hours after the attack and a SWAT team was called in, police said.

Benjamin Roman, an ultrasound technician, told KNBC-TV that before the stabbing, he saw the man, who had a dog with him and who might have been high on drugs because he looked anxious and was drenched in sweat.

After the hospital issued an “internal triage” code, Roman said he saw a doctor and a nurse who had been stabbed.

“The doctor looked (like) she was in pain,” he said. “There was a lot of blood and it looked like … he might have got her abdomen.”

The attack comes only two days after a gunman killed four people and then himself at a hospital in Tulsa, Oklahoma. The assailant got inside a building on the Saint Francis Hospital campus with little trouble, just hours after buying an AR-style rifle, authorities said.

The man killed his surgeon and three other people at a medical office. He blamed the doctor for his continuing pain after a recent back operation.