The University of Alabama in Huntsville campus is closed this week, and students there say they are shocked and confused after authorities say a biology professor opened fire on her colleagues on Friday

Three professors were killed after Amy Bishop allegedly shot them. Three other UAH professors were injured – two are still listed as critical in the hospital on Sunday and one had been released.

Several students said they had complained about Bishop’s courses, according to the Associated Press.

Julie Backer, a junior majoring in English, was in Bishop’s class for two semesters.

“When I first heard about the shooting, I figured it was just a student with problems,” Backer said. “But to find out it’s your own teacher? It’s hard to wrap your mind around it. It’s just sickening.”

UAH spokesman Ray Garner said Bishop, 42, had been denied tenure, and this was to be her last semester. Some have said Bishop opened fire because of a dispute over the issue of her firing during a biology staff meeting.

Authorities declined to discuss a motive at a Saturday news conference, according to the Associated Press, though Garner said the faculty meeting wasn’t scheduled to discuss tenure issues.

In a statement, UA System Chancellor Malcolm Portera said the entire system is saddened by the events at the Huntsville campus.

“In every way possible, we are assisting and supporting the University community, the families and friends of the victims, and the citizens of Huntsville,” he said.

Cameron Mortazavi, a freshman majoring in electrical engineering, said he was taking a physics exam in the building next to the Shelby Center when the shooting started.

He said he turned in his test expecting to talk to his classmates about how they did, but had about 30 text messages in his phone asking what happened and saw many emergency response vehicles and armed officers surrounding the area.

Mortazavi said he was appalled that the exam was not stopped.

“All these cell phones are going crazy, and nobody said anything … our professor didn’t stop the test,” he said. “And all the proctors were walking around, so nobody could check their phone because they’d think we’re cheating.”

UAH students received a text message around 4:30 p.m., Mortazavi estimated, even though the shooting had happened around 3:55 p.m.

Jeffrey Warner, a current UAH student, said he was frustrated about the delay of the alert system to inform students of the shooting.

“I was mad because they left us in the dark about this whole thing that affects everyone on campus,” he said. “What if Dr. Bishop had just walked out and not been stopped? Students would have had no idea of what was going on or where she could have gone.”

Erica Pruett, a senior majoring in biology, works in a research lab on the third floor of the Shelby center where the shooting happened. When she found out about the shooting, she said she was in disbelief, thinking it was some sort of cruel joke.

Pruett said she knew all of the professors personally, and described the biology department was like a family. While some students may find it hard to go back to campus, she said she is looking forward to getting back to work.

“Just being on the floor where it happened will be difficult,” Pruett said. “I will continually be praying for my faculty.”

Sara Powers, a freshman majoring in biology, said one of her professors, Adriel Johnson, who taught introduction to the health care profession, was killed in the shooting.

“I don’t know if we will even have that class anymore, because while there are multiple math and biology professors he was the only one who taught this class,” Powers said.

Reporters Will Tucker, Jessica Cheek, Amanda Sams and Haley Herfurth gathered this information. Editor Amanda Peterson compiled the reports. Information from the Associated Press was used in this report.