Gunfire erupted at a hospital on the outskirts of Philadelphia on Thursday, leaving one person dead and two wounded, Delaware County authorities said.

The incident occurred in a psychiatric unit at Mercy Fitzgerald Hospital, in Darby, Pennsylvania, a suburb of Philadelphia, about 2 p.m.

A 52-year-old female hospital case worker was killed.

One of the injured is the man who initially opened fire in the psych unit, whom authorities identified as Richard Plotts, evidently a patient at the unit.

Plotts is in critical condition and, according to county district attorney Jack Whelan, has a history of mental problems, the daily Philadelphia Enquirer reported.

The other wounded man is a doctor at the hospital, although he was not seriously hurt, authorities said.

In later remarks to reporters, Whelan said that officials believe the injured doctor may have shot the suspect multiple times after the man opened fire.

The suspect was subdued by hospital staffers at the scene and later taken into custody by police.

Whelan said that it was not yet precisely clear what happened and an investigation is under way.

After the shooting, the hospital was surrounded by police. EFE