CAMBRIDGE — Dozens of police officers descended on the Massachusetts Institute of Technology campus Saturday morning, moments after receiving a threatening message about a gunman that turned out to be a hoax.
But MIT students were not notified about the threat until more than an hour after it was first reported, when the school’s campus emergency messaging system sent a mass text message to students instructing them to remain indoors.
The unfounded report of a man armed with a rifle and dressed in armor inside the main building on MIT’s campus came from an electronic message sent to Cambridge police about 7:30 a.m. Saturday, authorities said at a news conference.
John DiFava, chief of MIT’s campus police, acknowledged the lengthy delay in communicating the threat to students when asked about it by reporters at the press conference.
“I have to look into it and find out the reason for the lag,” he said.
A spokeswoman for MIT declined to comment on the delay or to describe campus alert procedures, but the school said in a prepared 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.”
The statement said MIT sent a “precautionary text message” to students at 8:52 a.m, an hour and 24 minutes after Cambridge police first received the report about a gunman inside 77 Massachusetts Ave.
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.
Police said more than 30 officers responded to the scene and closed down Massachusetts Avenue, which runs through campus, between Vassar Street and Memorial Drive. They initiated a lockdown and conducted a search of the building, which yielded nothing unusual, authorities said.
“I can tell you for certain we did not have a person in the building with a gun,” Cambridge Police Commissioner Robert Haas said. “We have enough witnesses at this point in time to verify that. The incident that was reported did not take place.”
Police officials would not describe the contents of the message, or how it was received, though Cambridge police spokesman Dan Riviello said in an e-mail that the report did not come via one of the department’s anonymous tip submission platforms.
State Police spokesman David Procopio described the report as a hoax and said it alluded to a “possible barricaded armed suspect.”
Haas 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.
Calls to a spokeswoman for Leone were not returned.
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,” he said referring to the 2007 campus fatal shooting of 33 people, including the shooter.
Police had cleared the scene by 10 a.m., officials said at the news conference.
Authorities said there was no indication the hoax was related to Aaron Swartz, the Internet activist who recently took his own life.
Swartz was facing a federal investigation and possible prison time after downloading and freely distributing millions of academic articles from an MIT database.
His death galvanized supporters of open access to academic research and inspired sympathizers to hack MIT’s website.
On the MIT campus Saturday, many students said they were catching up on sleep during the event.
“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 serious threat.
“My roommate is a biology major, and he was worried about checking on some of his experiments,” said graduate student Ryan Cook, 25. “Mostly, people were just upset that they couldn’t come do work.”
But Cook said 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.”
Concern about the event echoed through the MIT community. A student who gave his name as Kristian F. said he received calls from three 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.”
Jeff Schiller, a former manager of MIT’s network who has worked with the university for 36 years, said it may be difficult for police to locate the perpetrator, depending on the person’s level of expertise.
“If the person who sent the message knows what they’re doing and doesn’t want to be found, you’re not going to find them,” he said.
The tipster could have used botnets — networks of computers in homes and offices infected with malware, malicious software — to bounce an electronic message through various untraceable addresses across the world, Schiller said.
The falsified tip could have also come from a “darknet,” he said, which lets users browse the Web with an anonymous Internet Protocol address.
The threat also could have come from a mobile device. Smartphones with outmoded or inadequate software can be compromised, Schiller said, allowing someone to remotely send e-mails and text messages from a phone without being identified.
“People who resort to crime usually aren’t the smartest in the world, so you can catch them,” Schiller said. “Where authorities start to have a problem is hacktivists. . . . Not to say that they can’t be caught, but there are plenty among them who will be smart enough to cover their tracks.”
Globe correspondents Gal Tziperman Lotan, Chris Stuck-Girard, and Jaclyn Reiss contributed to this report. Peter Schworm can be reached at email@example.com. Follow him on Twitter @globepete. Dan Adams can be reached at firstname.lastname@example.org. Follow him on Twitter at @Daniel