TUCSON, Ariz. (Oct. 28) - A student opened fire in a class at the University of Arizona nursing school Monday, killing two professors and another bystander before apparently taking his own life, school officials said.

The attack sent scores of students rushing toward the doors of the school in central Tucson, many of the screaming as they fled. Police went room to room looking for more victims and later called in the bomb squad to search the building.

The gunman was identified by university Vice Provost Elizabeth Irvin as Robert S. Flores, a Gulf War veteran who was apparently flunking out of the nursing program. He apparently committed suicide after the attack, Police Chief Richard Miranda said.

Police did not disclose how the victims died or what their relationship was to Flores, if any. They said the victims were found in two different locations inside the school north of the university’s main campus.

Police also refused to identify the victims, though a university spokeswoman said they included two female professors.

Bomb squad members were called in after a backpack or package was found underneath the gunman’s body. The suspect had earlier threatened to blow up the building, though it was unclear when the threat was made, Miranda said. A bomb-sniffing dog reacted to the suspect’s car in a nearby parking lot.

The college and nearby buildings were evacuated.

Irvin said she didn’t know how long Flores had been in the nursing program, but he had failed a pediatric class and was struggling in a critical care class.

Flores worked at the Southern Arizona Veterans Administration Health Care System as a licensed practical nurse who was employed by a nursing agency, said Spencer Ralston, associate director for health care system.

Ralston said Flores had begun clinical training at the Veterans Administration last Wednesday.

"We don’t show anything in our records that indicates good or bad (performance)," Ralston said.

Lori Schenkel, who was in the building during the shootings, said two different students banged on her classroom door and told everyone to get out.

"We ran out of the building and there were police telling us to run away," Schenkel said.

Anu Nigam, a 29-year-old graduate student, said she and her husband were outside the building waiting for a shuttle bus when a woman came out of the building with a cell phone, trying to dial and screaming that there was a man with a gun in the building. Police were at the scene within seconds.

"A group of people were crying and running desperately to get out of the building," Nigam said. "They were crying, tripping over one another, falling down."

Nigam’s husband, Vishwas Seshadri, 27, estimated they saw 50 to 60 people scramble to get out of the building before police swarmed in and shooed them away.

Police escorted groups of students, faculty and administrators in shuttle buses to the Alumni Building, where counselors were being made available.

Dana Weir, a spokeswoman for the alumni foundation, said students and faculty looked shaken, and people in her office were just trying to make them comfortable.

University President Peter Likens called the shooting an isolated incident. He said there were no immediate plans to change security procedures at the 34,000-student university, which includes the 380-student nursing school.

"I don’t now believe there’s any reason to imply a deficiency of security either in that building or on this campus," he said.