It happened on Monday, one day after the brutal and tragic shooting massacre in Las Vegas that killed at least 59 and wounded 527 people. A professor at the University of Southern California reportedly suffered an “episode” as she was “distraught and upset” after hearing news of the Mandalay Bay shooting, urging students to “take cover” as there was an “active shooter” in Fertitta Hall on the campus. That professor, later named as Amy Granados, has since been arrested for the false alarm.

Students call 911 after professor warns of ‘active shooter’

After several students called 911 to report what they believed to be an “active shooting,” the response was rapid, with police on campus soon after the alert had been given.

Helicopters flew over the university, surveilling the scene, as a SWAT team searched the building where the “active shooter” was reported to be holed up. KABC-TV reports students were evacuated and a full lock-down of the campus was put in place while officers were investigating the report. However after police found no evidence of an active shooting, they cleared the campus, allowing the students to return.

After police searched the grounds, the LAPD headed to Twitter to say their investigations at Usc had shown was “no danger to the community.”

While some students had believed a drill might have been ongoing at the time of the alert, Deputy Chief Phillip Tingirides went on to say police did not believe it had been a test or drill, adding that the professor had been arrested.

Student reactions to false 'active shooter' alert

USC’s student newspaper, the Daily Trojan, quotes one student, Christopher Rawlings, as saying Granados had told them of the alleged active shooting while teaching a business class. He said the professor ran from the room, telling the students she was getting help and leaving them alone in the room. They remained in that room for one hour before the LAPD released them.

Rawlings said he believed it was a drill and that the professor had been acting. However, as he started getting messages, asking if he was OK, the incident began to get more real for the students.

Another student, Remy Porsella, said he was in Fertitta Hall at the time, when he suddenly heard people screaming and saw hundreds of students running from the building, adding that it was a “full panic” situation.

In a statement on Monday evening, the chief of the Department of Public Safety at USC, John Thomas, went on to laud the rapid response by both his department and the Los Angeles Police Department. He went on to say that a faculty member had falsely told her students of an active shooter in the building and that she had since been detained by the LAPD and is undergoing a mental health evaluation.