A doctor told police that a patient fatally shot a caseworker at their hospital complex before the doctor pulled out his own gun and returned fire, wounding the assailant, a prosecutor said on Thursday night.

Dr Lee Silverman, a psychiatrist, was grazed in the head during the gunfight in his office with patient Richard Plotts, according to District Attorney Jack Whelan.

Whelan identified the caseworker killed on Thursday afternoon at Mercy Fitzgerald Hospital as Theresa Hunt, 53. Hunt, who was from Philadelphia, had accompanied Plotts to an appointment with Silverman at a psychiatric crisis center adjacent to the hospital in Darby, just southwest of Philadelphia, authorities said.

When the caseworker was shot, Silverman "crouched down behind the desk to avoid being shot," Whelan said. "He was able to reach for his weapon, and, realizing it was a life-or-death situation, was able to engage the defendant in the exchange of gunfire."

A struggle ensued and spilled out into the hallway, Whelan said. Another doctor and a caseworker jumped in to help Silverman and secure Plotts' weapon, he said.

The motive for the shooting remained unclear late on Thursday, although Whelan said Plotts, of Upper Darby, might have had issues with the doctor over his treatment plan. It was unclear if that's why Silverman was armed, apparently against hospital policy.

"We do believe that there were some issues between the doctor and the patient, but whether or not he actually feared him is unclear," the prosecutor said. "From all accounts, he would have acted in self-defense."

Whelan said that Plotts, 49, was still in surgery on Thursday evening at the Hospital of the University of Pennsylvania, while Silverman had been treated and released. Telephone calls to the doctor's home went unanswered.

Plotts does not have a listed home phone number. Court records in Delaware County show a man of the same name and age with a lengthy criminal record, but Whelan was uncertain if they represented the same person.

The hospital has a policy barring anyone except on-duty law enforcement officers from carrying weapons on its campus, a spokeswoman for the Mercy Health System said.

But Yeadon Police Chief Donald Molineux said that "without a doubt, I believe the doctor saved lives".

"Without that firearm, this guy could have went out in the hallway and just walked down the offices until he ran out of ammunition," Molineux said.

(China Daily 07/26/2014 page11)