(NEW HAVEN, Conn.) -- Yale University was put on lockdown after an anonymous male called 911 Monday morning to say his roommate was on his way to the campus with the intention of shooting people, according to officials. New Haven Police Officer David Hartman said at a news conference Monday that there has been no gunfire or injuries, but authorities are interviewing several witnesses who said they saw someone with a "long gun."
No one has been detained and there is no description of a possible suspect yet, Hartman said.
The anonymous caller made the phone call from a pay phone, spoke about his alleged roommate and then hung up.
Officials from Yale Police, New Haven Police and Connecticut State Police are on scene and "actively searching for any gunman," according to the university's website.
The school is on its November break, meaning there are fewer people on campus than usual.
Yale University sent out an alert Monday morning instructing people to shelter in place after confirming reports of a person with a gun on or near Old Campus.
"Confirmed report of person with a gun on/near Old Campus. SHELTER IN PLACE. This is NOT a test," the alert said.
New Haven Police received an anonymous call from a phone booth reporting a person on the Connecticut campus with a gun, the university said in an alert at 10:17 a.m. ET.
The report was confirmed in an alert at 11:02 a.m.
The university has over 11,000 students and is located about 80 miles northeast of New York City.
This a developing story. Check back for updates.
Copyright 2013 ABC News Radio