• Call to police prompted campus lockdown lasting several hours • Officers received call saying gunman was on way to school

This article is more than 6 years old

This article is more than 6 years old

Connecticut police are investigating whether a Monday morning call alerting them to a gunman on the Yale University campus was a hoax.

The call prompted a school lockdown lasting several hours. Students and staff were ordered to shelter in place at the university after officers received an anonymous call at 9.30am.

The caller said their roommate was heading to the school with a gun, prompting police to flood the campus and begin an exhaustive room to room search of university buildings.

The focus of the investigation switched on Monday afternoon, however, with police attempting to track the person who made the initial phone call. The caller never stated their name but called from a pay phone in the 300 block of Columbus Avenue, close to Yale campus, KPTV reported.

New Haven police chief Dean Esserman told a news conference Monday afternoon that the campus is safe. The lockdown was lifted at 4.40pm.

Esserman said once the caller is located he or she will face charges. He said police would continue to search for several hours, following up on numerous leads.

"Once we have geared up, we don't gear down," Esserman said.”[The] all-clear will not be given until it is certain it is all clear."

Television footage showed emergency vehicles outside campus and images circulated on social media of armed police and agents from the federal Bureau of Alcohol, Tobacco, Firearms and Explosives patrolling the scene.

Amid the confusion, Yale’s emergency management website said there were “confirmed reports of a person with a gun on Old Campus”.

However, police said that a witness may actually have spotted a police officer or other law enforcement agent.

"They may not recognize that person is law enforcement personnel," New Haven officer David Hartman said, according to KPTV.

Many students had left the university ahead of Thanksgiving. Many of those who remained were afraid to open their doors to police, which extended the length of the search, the Associated Press reported.