Albert DeFluri was in the Angell Hall complex between 12 p.m. and 1 p.m. Thursday dressed in fatigues, a black jacket, a gas mask and an empty ammunition pack, causing a panic and an armed police response. The Engineering junior, who only agreed to speak to reporters anonymously before identifying himself publicly on Facebook, said his actions were “more or less a joke.”

“Knowing the extent of how things went, I may have second guessed myself. I didn’t expect a big commotion to happen,” he told the Daily.

DeFluri was holding a sign with a cat picture that read, “Love is in the air? Get out the gas mask.” He said he saw the “grumpy cat” meme online Wednesday night and decided to “take it up another level.”

University Police officers entered the complex carrying assault rifles, later confronting DeFluri outside the complex. He said officers told him his act was “a bad idea in the wake of events this year.”

University Police spokeswoman Diane Brown said no one was formally evacuated, and people entered and exited the building freely during the response. However, several witnesses reported that UMPD officers told them to leave the building, and an officer stood guard at an entrance to Tisch Hall while the response transpired.

Brown was unaware if initial reports to UMPD about the incident suggested that DeFluri might have had a firearm.

“I kind of realized, it’s like, yes, it’s Valentine’s Day, it’s really nice,” DeFluri said. “On the other hand, I kind of see why these single people that are a little distraught that all these people are doing nice things and the rest of them … they’re not really doing anything.”

“I decided to wear the sign around my neck and the gas mask around,” he continued. “You know, show people the sign, show them I’m not up to anything bad.”

Cynthia Alexander, a facilities manager for humanities and social sciences, and a University police officer went around the building, alerting department offices and administrators. An all-clear was given shortly before 1:00 p.m., after which Alexander said business was back to normal.

DeFluri said he was acting alone, adding that most people were not alarmed by his actions — people smiled, laughed and asked to photograph him.

“I thought it was funny. You couldn’t see my expression, but I was laughing the entire time under my mask,” he said.

Facebook and Twitter were buzzing with posts reporting various sightings of the DeFluri and police in the building.

Communications Associate Prof. Scott W. Campbell, who specializes in the social consequences of new and mobile media, pointed to the heightened sensitivity of today’s society as a main reason for students updating their friends and followers via social media.

Campell said school shootings, including those at Columbine High School and Sandy Hook Elementary School, laid “a foundation of heightened sensitivity about gun violence, and when these things happen people are using new media to kind of crowdsource the story.”

In light of the armed response, DeFluri said he believes Thursday’s incident was blown out of proportion.

“I honestly think it’s an overreaction,” DeFluri said. “It’s kind of sad recent events made people somewhat paranoid about it.”

LSA freshman Nicholas Vaneck said he was exiting Angell Hall, at the entrance nearest to State Street, at about 12:05 p.m. when he saw two police SUVs "flying through" the sidewalks in front of the University Museum of Modern Art. An officer came out from each vehicle, Vaneck said, adding that they grabbed rifles and ran into Angell Hall.

LSA freshman Marissa Allegra said she was sitting in front of the Fishbowl waiting for class when she saw UMPD officers roaming the hallways.

“I was still unsure of what was going on,” Allegra said. “Initially, I was extremely frightened and concerned that I would be in one of the rare cases of a school shooting or violence.”

Institutions of higher education across the country have tightened security and have re-examined emergency response plans in the wake of a series of high-profile mass shootings. The 2007 incident at Virginia Polytechnic Institute and State University was the second-largest mass shooting at a school in U.S. history, taking the lives of 32 people and wounding 17 others.

Tony Holt, Wayne State University police chief, outlined the factors that go into making tactical decisions similar to UMPD’s armed response.

“In a University setting, you have to be very proactive,” Holt said. “At Wayne State, there are no weapons allowed, (so) if we got a call, with even the suspicion of someone having a weapon on University property, we would probably first send out a text alert to the campus community and then launch a full tactical operation.”

Like WSU, the University prohibits weapons on campus.

Holt said that whenever there is even the possibility of danger in a campus setting, immediate action must be taken to ensure student safety and minimize displacement, even if the presence of a weapon cannot be confirmed.

“Whenever a gun is even a possibility, we have to err on the side of caution and safety because you don’t get second chances in situations like this,” Holt said.

Though an armed police response may have scared some students, Holt said it’s better to be safe than sorry, comparing it to sending officers to investigate if a fire exists instead of a fire truck.

“We don’t take anything as a joke. A lot of people may think it’s overkill for cops to come in full tactical gear, but student and campus safety has to be our number one priority at all times,” Holt said.

The proximity and credibility of incident reports is crucial in determining the course of action to be taken, said Ronald Haddad, chief of police in Dearborn, Mich.

“You can always scale back the investigation when it’s determined that he’s not a threat, but when you don’t know what you’re dealing with, you have to error on the side of caution,” Haddad said. “Obviously it would have been unacceptable if the tip had been discredited and then the suspect turned around and shot up a bunch of young people.”

Haddad said UMPD’s immediate, armed response was necessary because DeFluri was in a campus environment with a large, dense population.

“I understand the validity of the first amendment and this young man’s right to express himself, but imagine if he’d gone to an airport (in camouflage and a gas mask),” Haddad said. “He would have been immediately met by police, Department of Homeland Security, Transportation Security Administration, and everyone else, because you can’t take those kind of risks.”

The 2007 Virginia Tech shooting and last year’s incidents in Aurora, Colo., and Newtown, Conn., were all perpetrated by people under the age of 25. There has been speculation that the shooters in these cases were all suffering from some form of mental disease.

According to a Jan. 22 video report by CBS News, police units across the country are retraining officers to better confront uncertain situations, especially when there is an active shooter is involved. In a training exercise at George Mason University, officers moved in without waiting for backup and swept the hallways searching to find the “shooter.”

At the University of Michigan, police appeared to respond in a similar manner. Regular, uniformed officers swept the hallways as a plainclothes commanding officer coordinated units around the building from outside.

In September, the University of Texas and North Dakota State University both responded quickly to bomb threats on their campuses, forcing the evacuation of tens of thousands of students. No suspicious items were found in both cases, but administrators acted quickly to warn students via text, e-mail, and website postings. No such warning or communication was issued immediately at the University of Michigan on Thursday, though UMPD's website was updated with information periodically.

UMPD alerts the University community through the Emergency Alert System when it feels a situation poses a campus-wide threat.

Brown said the system was not activated in response to Thursday's event because reports of DeFluri were limited to one building.

“The Emergency Alert System is to used when there is a confirmed, imminent threat that the majority of people need to take cover,” Brown said. “Our campus is different for one single building. It was one building, so officers were doing their best to deal with that one building.”

Universities and colleges across the country have also faced false alarm situations from internal miscommunication. Last year, Tulane University erroneously sent an emergency text message to students warning of a shooter at an unspecified location. Officials later retracted the message and wrote that it was accidentally released during a training session for the emergency response system.

In 2011, U.S. Capitol Police in Washington, D.C. responded to reports that a gunman had been spotted near the Georgetown University Law Center. Officers later found a gun nearby, but determined it was unrelated to the incident and Georgetown released an “all-clear” message to its campus community within a few hours.

—Editor in Chief Andrew Weiner, Managing News Editor Adam Rubenfire; Daily News Editor Peter Shahin; and Daily Staff Reporters Giacomo Bolgona, Matt Jackonen and Stephanie Shenouda contributed reporting.