A gunman stormed a classroom at the University of Arizona Monday, killing three people, including two professors, and then shot himself. The shooting occurred at UA’s College of Nursing in Tucson.

Immediately afterward, a sizeable portion of the UA medical campus was evacuated, and a major traffic corridor was shut down.

University Vice Provost Elizabeth Irvin identified the gunman as Robert S. Flores, a Gulf War veteran who was apparently frustrated over his academic status at the nursing school.

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

According to the Arizona Daily Wildcat, Flores entered the classroom at approximately 8:40 a.m. during exams and proceeded towards one professor.

At this point, he told the professor, “It might not matter to you, but it matters to me,” referring to his academic status in the school.

Flores then fired three shots, killing the professor before walking to another professor nearby.

“Make your peace with God,” he reportedly said. He proceeded to kill that professor as well.

“He had some issues last semester that kept him from completing his classes,” Melvin Thornhill, whose wife attended the class and called him shortly afterward, told the Daily Wildcat. “It didn’t even click right away that he wasn’t even in that class.”

Police reported the victims were found in two different locations within the school.

Flores had earlier threatened to blow up the school, and when a backpack was discovered under his body a bomb squad was called in to examine the bag.

A witness to the shooting said the suspect was disgruntled over being barred from participating in a midterm examination.

However, university officials said there was no indication in their records that Flores was in academic distress. Flores had failed an earlier class in pediatrics and was struggling in a critical-care class, according to Ralston.

A wave of panic spread throughout the school in the moments after the shooting.

Witnesses standing outside the building where the shooting took place said they saw scores of people running out of the building, some running over others who had fallen. Another witness who was taking an examination on the fourth floor said she heard about 15 shots fired.

Arizona University President Peter Likens viewed the shooting as an isolated incident and does not expect any security changes at the Tucson campus.

CBS affiliate KOLD reported that students ducked under their desks after the first shooting. After the gunman killed the second professor, he reportedly told the students they were going to be taken hostage but then allowed them to exit the building.

“I am personally comfortable that there is no further risk,” Likens told CNN. “It’s an intensely personal tragedy and trauma.”