BOSTON — Yale University lifted a lockdown on Monday after a police search of its campus in New Haven, Conn., found no evidence of a gunman, despite an anonymous caller’s claim that his roommate had headed to the Ivy League school to shoot people.

“This is so far an unconfirmed report,” said David Hartman, spokesman for the New Haven Police Department. “We have not identified a suspect in this case.”

No one was injured and no shots were fired at any time during the incident, Hartman said. He added that police now believed that a witness who reported seeing a person carrying a gun most likely had seen an armed police officer.

The department received an emergency call at 9:30 a.m. from a man on a pay phone near Yale University who stated that his roommate was en route to the campus “with the intention of shooting people,” Hartman told reporters.

Police locked down a large area of downtown New Haven around the school and conducted a room-to-room search of parts of its campus, located in downtown New Haven.

“We have not yet identified that caller,” Hartman said. “He did not identify himself when asked, he did not remain on the 911 line when asked.”

Televised images showed police officers arriving on a largely deserted campus, since most students had gone home before the Thanksgiving holiday. New Haven and Connecticut State police went to the scene, Yale said.

Some 11,250 students attend the prestigious university.