Yale Lockdown Caused By Hoax, Police Say The campus was locked down afteran anonymous 911 call was placed this morning.

Nov. 25, 2013  -- A day-long lockdown of the Yale University campus was lifted this evening after authorities determined that a call warning of a gunman intent on shooting people was likely a hoax.

Yale's New Haven, Conn., campus was put on lockdown after an anonymous male called 911 this morning to say his roommate was on his way to the campus with the intention of shooting people, according to officials.

New Haven Police Chief Dean Esserman said there was "malicious intent" behind the call. However, after a search of the campus did not reveal any threats, he said authorities are "leaning toward this being a hoax."

Esserman said once police identify the caller, that person "will face every charge possibly imaginable."

The anonymous call was placed from a phone booth and the university sent out an alert at 10:17 a.m. ET.

At a news conference earlier today, New Haven Police Officer David Hartman said authorities interviewed several witnesses who said they saw someone with a "long gun."

After speaking with some of the witnesses, Hartman said, "Some of those witnesses in all probability saw police officers with long guns instead of a suspect."

Yale Police Chief Ronell Higgins said this incident showed that the school's emergency preparedness plan worked well.

"You have to exchange business cards with local law enforcement and schools before incidents like this one," he said. "We are always in constant communication."

An email was also sent by Yale's dean to notify parents of undergraduate students of the threat.

The school is on its November break, meaning there are fewer people on campus than usual.

An alert send by the university this morning instructed people to shelter in place.

"Confirmed report of person with a gun on/near Old Campus. SHELTER IN PLACE. This is NOT a test," the alert said.

A search of the campus dorms was hampered because some students refused to open their doors to police, fearing that the person knocking was not really a police officer.

The university has over 11,000 students.