A disgruntled former nurse at a state mental hospital here opened fire on two hostages this morning after a two-day standoff with police, killing one nursing supervisor and critically injuring another.

The gunman, Dennis Czajkowski, was fired from Norristown State Hospital in April after working there for more than a decade. Angry about how he had been treated, Czajkowski on Wednesday took two former supervisors who may have had a role in his dismissal hostage and demanded an investigation into his firing.

But after two days of negotiations, Czajkowski started shooting the two women about 8:45 a.m. today, just moments after state police broke a window to get a better look at the room where the hostages were being held.

"As soon as the window broke, he opened fire," State Trooper Robert Whitbeck said this morning at a news conference at Norristown State Hospital, where local police and state police SWAT teams had been camped out since the drama started unfolding. After the shots were fired, police immediately entered the room and subdued Czajkowski without firing any shots.

Carol Kepner, 54, of Wynnewood, Pa., was pronounced dead at the scene and Maria Jordan, 37, of Norristown, suffered multiple gunshot wounds but was expected to recover. Czajkowski was treated at the hospital for minor injuries.

Police Capt. Thomas LaCrosse, at a news conference late this afternoon, said police became more concerned for the safety of the hostages early Friday, after Czajkowski started referring to the two women as "suspects" instead of "witnesses" as he had earlier in the standoff, and refused to let either police or family members speak to the women to determine their condition.

LaCrosse said it was "routine" for the State Police Special Emergency Response Team to break windows to gain visual access in situations such as this, but no suspect has ever responded by shooting.

In light of the tragic outcome, however, residents of this working-class community and employees of what is the state's largest mental hospital questioned the police decision to break the window, and to do it without alerting Czajkowski, who had been awake for more than two days and was getting increasingly agitated.

"The idea is to save folks being held hostage," said Denise Kennedy, a psychiatric aide at the facility who had come to pick up her paycheck Friday morning. "They triggered him to pull the trigger; they definitely set him off," she said of the police actions.

Charles Vaszily, who lives across the street from Gate 5 of the hospital and watched the drama unfold from his front porch, said he thinks there should be a "good investigation not conducted by the state police" into the tragic end of the standoff.

"I would want to know why, if they lost sight of him in the building, why they would want to agitate him by breaking a window," Vaszily said. "I think the state police made a mistake, and they caused innocent people to lose their lives."

Czajkowski, of Collegeville, Pa., was dismissed from his job as a registered nurse after attempts were made to help him resolve personal problems, said Susan Aspey, spokeswoman for the State Department of Public Welfare.

Aspey said she did not know whether Kepner, nurse manager at the Norristown Hospital, or Jordan, director of nursing, were directly involved in Czajkowski's dismissal, and said she was not aware of any threats made by him since he was fired two months ago.

The standoff started just before noon Wednesday when Czajkowski went to Jordan's office and took the women hostage. During 46 hours of negotiations, Czajkowski had asked for an investigation into his dismissal, but LaCrosse said the gunman was not always lucid and had a "whole litany of complaints" he wanted addressed. Nonetheless, LaCrosse said, "We were willing to sit there as long as we felt the hostages were not threatened."

LaCrosse also said that Jordan was shot early during the ordeal in the wrist and ankle, although police at first believed Czajkowski had fired harmless shots into the air.

CAPTION: A Medevac helicopter leaves Norristown State Hospital in Pennsylvania after hostages were shot during standoff. Suspect Dennis Czajkowski, who had worked there about a decade, was subdued by police.

CAPTION: Unidentified employees of Norristown State Hospital listen as authorities tell them a former co-worker had shot two hostages, one fatally. The suspect reportedly was angry about how his firing had been handled.