CAMBRIDGE—The unfounded report of a gunman inside the main building on MIT’s campus came from an electronic message sent to Cambridge police around 7:30 this morning, authorities said at a news conference today.

The report sparked a lockdown and an immediate search of the building, which found nothing unusual.

Advertisement - Continue Reading Below

“A thorough search of the building was conducted looking for that armed individual,” said John Boyle, a spokesman for the Cambridge police. “After the thorough search, he was not located and the scene was deemed safe.”

Boyle would not describe the contents of the threat, or how it was received, though Cambridge Police spokesman Dan Riviello later said in an email that the threat did not come via one of the department’s anonymous tip submission platforms.

Boyle said about 30 city and campus police officers responded to the threat within “seconds.”

MIT students were notified electronically about the threat by the school’s campus emergency messaging system well over an hour after Cambridge police alerted MIT.

John DiFava, chief of MIT’s campus police, acknowledged the lengthy delay in telling students about a possible gunman on campus.

“I have to look into it and find out the reason for the lag,” he said.

A spokeswoman for MIT declined to describe campus alert procedures, but the school said in a statement that “MIT Police and other parts of the MIT administration will, as part of standard operating procedure, conduct an after-action review of MIT’s police and communications actions during this event.”

State Police spokesman David Procopio described the false report as a hoax. He said the report described a “possible barricaded armed suspect.”

Robert Haas, the Cambridge police commissioner, said detectives were working to determine who was responsible.

“We are taking this very seriously,” Haas said. “This investigation is still very much active and there are investigative leads we’re following. If we do indeed identify the person, we will be seeking criminal charges.”

Haas said he had been in discussions with Middlesex District Attorney Gerard T. Leone about the case, and that the FBI and Secret Service are assisting in the investigation.

Authorities said they had no doubt the report was false.

“I can tell you for certain we did not have a person in the building with a gun,” Haas said. “We have enough witnesses at this point in time to verify that. The incident that was reported did not take place.”

The false report prompted a massive law enforcement response and forced the lockdown of the campus.

At 7:28 a.m., the Cambridge police reported of a “possible person with gun” on Twitter. Minutes later, police closed Massachusetts Avenue, which runs through campus, from Vassar Street to the bridge over the Charles River.

Shortly before 9 a.m., MIT sent two emergency alerts via text message.

“Multiple law enforcement agencies on campus in response to a report of a person with a gun on campus, further info on the Emergency Web Page,” the messages read. “Report suspicious activity to campus police dispatch.”

At 9:22, MIT posted on its website reports that a “there was a person with a long rifle and body armor” in the main building, and urged students to stay indoors.

Zach Wener-Fligner, 21, a junior at MIT, said he first received an alert at 8:51 a.m., as did other students interviewed by the Globe.

“It’s a little worrisome,” he said of the delay. “But I assume the relevant area was locked down.”

“I definitely freaked out a little bit,” upon hearing the news, he said. “I thought of Virginia Tech.”

At 10:19 a.m., police in Cambridge posted on Twitter that the “scene is clear.”

Authorities said at the press conference that there was no indication the hoax was related to Aaron Swartz, the Internet activist who took his own life.

On the MIT campus today, many students said they were catching up on sleep during the incident, which ended by 10 a.m.

“Almost everybody sleeps in on Saturday mornings,” said Kezi Cheng, a 19-year-old sophomore at the school. “Maybe if it had happened during a weekday, there would have been more panic.”

Other students said the lockdown was more of an inconvenience than a worry.

“My roommate is a biology major, and he was worried about checking on some of his experiments,” said MIT graduate student Ryan Cook, 25. “Mostly, people were just upset that they couldn’t come do work.”

But Cook acknowledged the apparent delay in notifying students about the threat was troublesome.

“They should have done it better,” he said. “But I feel totally safe here. It’s no more dangerous than other parts of the city.”

Concern about the incident echoed through the MIT community. A student who gave his name as Kristian F. said he received calls from three different family members who had seen media reports and were worried about his safety.

“I pushed my fridge in front of my door and went back to sleep,” he said, describing his reaction to the news. “Security’s pretty tight in the dorms here ... . Everyone is just wondering why this happened and who did it.”