The University of Colorado Boulder Police Department is investigating a potential swatting incident at Norlin Library on Monday following a campus-wide shelter in place order. 

Initially, campus police were investigating a report of shots fired at the library, according to university alerts. 

The campus police alerted all students and teachers to shelter in place on the main CU campus just before 5 p.m. That shelter-in-place order was lifted at 5:40 p.m.

Police said there are no signs of injuries or a suspect.

Students gathered on campus near the library Monday after being evacuated from both the library and Sewell Hall, video calling their friends and families, taking photos of the dozens of police vehicles and armed officers on campus and talking amongst each other about the incident.

Officers stopped students trying to walk toward the library, directing them other ways. Some students were sheltered in place in the library, only allowed to leave after 7 p.m., a campus alert said. 

Junior Lidiya Haile and senior Roshni Nandi were both studying in Norlin Library when they were suddenly told to evacuate.

Neither of them heard shots fired, they said, and nobody told them what was going on. 

“One of the library staff just came in and lady just came in and told everyone to be quiet,” Haile said. “She’s like, you guys need to evacuate right now, like, quickly and calmly, like, get out from here.”

They both rushed out of the library and waited outside together with friends as campus police officers, Boulder County Sheriff’s Office deputies and Boulder Police Department SWAT teams flooded campus.

“I was pretty scared, so I ran out,” Nandi said.

Nandi, Haile and another senior, Abhiyan Barailee, were alarmed by the sheer amount of police presence, which rivaled any police presence they’ve seen for any incident at CU in their three years at the university, they said.

“There are always cops on campus when something is happening, like two or three cop cars, but there’s like, 50 plus different type of vehicles,” Nandi said.

At least four times since Thursday, major college campuses have been disrupted by hoax “active shooter” calls, known as “swatting.” Included were Pennsylvania, Villanova, South Carolina and Tennessee, according to MSN. 

FBI detectives are involved, according to published reports from near the University of Tennessee at Chattanooga, MSN reported.

Chancellor Lori Bruce, in a letter to the community, said Thursday’s “original 911 call did not originate from campus. This incident was a criminal act, intended to be disruptive and cause chaos, but at no point was there a real threat to campus.”