New Haven police say it may have been a combination of a hoax and mistaken identity.
The lockdown and shelter-in-place advisory were issued Monday after an anonymous caller told police his roommate was headed to the Ivy League school to shoot people. The initial call came in at 9:48 a.m. EST
"The caller, who did not identify himself, told New Haven police that his roommate had a gun on the Yale campus," Yale Vice President Linda Koch Lorimer said Monday evening in a statement. "New Haven police shared this information with Yale police, and both responded immediately, scouring the campus and the location of the phone booth off campus from which the anonymous call was placed."
The university sent out an alert announcing police would be doing a room-to-room search starting with the residential college areas.
Students have been on break since Saturday and classes do not resume until Dec. 2, but police were advising people on campus, including staff members, to shelter in place for much of the afternoon.
A few minutes after the alert went out, a Yale employee called police to report she saw a man walking on Old Campus with a rifle.
"It now appears that the man she saw may have been one of the early responding police officers carrying a rifle," Lorimer said. "Besides this caller, no one reported seeing a shooter or a person with a gun on campus. Nevertheless, we kept the campus on lockdown while the search for a potential gunman continued."
Police say they're searching for the person who made the initial phone call.
"As the chief of New Haven police made clear in the news conference this afternoon, if it was a prank call that started this chain of events, the authorities intend to prosecute the individual to the fullest extent of the law," Lorimer said.