The seven-hour lockdown at Yale University is over.
It was issued soon after a man made an anonymous call to police at 9:48 a.m. from a phone booth in the 300 block of Columbus Avenue and said his roommate was on his way to the Ivy League school to shoot people, police said.
Police said this afternoon that they believe the call was a hoax, but they were conducting a room by room search of thousands of rooms at Yale.
"We don't have the luxury of going on a hunch, so we are gong to run this down to ground all the way," New Haven Police Chief Dean Esserman said.
Police said they have identified witnesses, as well as others, who were not sure whether the person they saw with a gun was a citizen or a police officer, so they took no chances and police are maintaining a perimeter around campus out of "an abundance of caution."
Police also said there were reports from people on campus seeing someone on a roof or someone, but it turned out to be someone who was smoking a cigarette.
"Nobody has been hurt, nobody has been found, but the day is hardly over," Esserman said. "Because, until we are satisfied that perhaps a police officer was mistakenly seen with a gun, and not a civilian seen with a gun, we are going to err on the side of caution. I want to repeat -- nobody has been shot. Nobody has been hurt. Nobody has been apprehended with a gun. ... But in this day and age, when there is a call, it behooves us to over-react and not under-react."
The caller who triggered the massive police response did not identify himself and only stayed on the phone with dispatchers for a few seconds before hanging up, David Hartman, of the New Haven police department said.
Immediately after receiving the call, Yale University ordered a shelter-in-place/lock-down order and state police, the FBI, ATF and other federal agents joined Yale and New Haven police in the investigation.
Esserman said during a news conference this afternoon that police have tracked down the call and they are tracking down the person who made it.
"I'm not, and Chief Higgins is not going to walk away and go home tonight until everybody we're responsible for keeping safe is safe," Esserman said. "And thought it is starting to tilt in the direction of an innocent mistake, it started with a purposeful and malicious call and the New Haven Police are going to track down the person who made that call, we're going to find the person who made that call, we're going to put handcuffs on the person who made that call."
Yale's November break started on Saturday, but several students remain on campus.
One Yale student said she was the only person in her suite when the lockdown was issued. For four hours, she remained inside while her father waited outside to take her home for the Thanksgiving break.
After police knocked on the door and searched her room, she was allowed to leave.
This is a situation that played itself out over and over again today as police do a room to room search that started with the residential college areas.
"When (police) knock on your door, a Yale Police Officer will slip their Yale ID under the door. Please cooperate. In some cases, Police may use keys, but they will identify themselves. Shelter in Place continues," an alert the university issued at 1:45 p.m. said.
Police said this afternoon that Old Campus was considered "the hot zone," and the search could take hours.
Just before 2 p.m., the SWAT team was entering Calhoun College, at College and Elm streets. It is one of Yale's 12 residential colleges.
Police are also asking drivers to stay away from the area as the emergency response continues and said the New Haven Free Public Library is closed.
The downtown area remains congested and slow moving, so people are asked to avoid the area if possible.
Businesses were also affected. Hartman said businesses on Chapel Street, between College and High streets, were closed.
"At the end of the day, we can always sell more soup and more salads and more food, but we can't replace bodies, so that's all we cared about,"Claire Criscuolo, owner of Claire's Corner Copia, said.
They have since reopened.
Anyone with information is asked to call 911 immediately.