A half-naked man suspected in the slayings of four people at a Waffle House remained on the run Monday, and authorities said he may be armed with one of the guns seized from him last year after he tried to enter the White House to see President Donald Trump.

More than 80 Nashville police officers continued to search for Travis Reinking, joined by agents with the FBI, the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives and troopers with the Tennessee Highway Patrol.

Reinking was wearing only a green jacket when he opened fire with an AR-15 in the Waffle House parking lot and then stormed the restaurant, police say. Four people were killed and four others were injured before a quick-thinking customer wrestled the assault weapon away, preventing more bloodshed.

Metropolitan Nashville Police Chief Steve Anderson said at a news conference that Reinking, 29, was last seen Sunday around a wooded area near an apartment complex where he lived, wearing only pants and no shirt or shoes.

Anderson said it’s not clear why Reinking opened fire on restaurant patrons, though he may have “mental issues.”

He may still be armed, Anderson said, because he was known to have owned a handgun authorities have not recovered.

James Shaw, Jr. says he didn’t mean to be a hero when he wrestled a gun away from the Nashville Waffle House shooting suspect early Sunday. Police say Shaw, who was wounded, saved lives. (April 23)

“He’s on foot,” Anderson said. “Unless he’s been picked up by a car, he would be fairly close. We don’t want to alarm people, but certainly, everybody should take precautions. It could be he’s in an unoccupied house. We want everybody to be concerned. Neighbors should check on each other.”

Nashville public schools will go into “lock-out” mode if Reinking isn’t found in time for class Monday, officials said. That means students will be free to move about the building, but no guests or visitors will be allowed to enter.

As the search continued, authorities in Illinois shared past reports suggesting multiple red flags about a disturbed young man with paranoid delusions.

In May 2016, Reinking told deputies from Tazewell County, Illinois, that music superstar Taylor Swift was stalking him and hacking his phone, and that his family was also involved, according to a report released Sunday.

Another sheriff’s report said Reinking barged into a community pool in Tremont, Illinois, last June, and jumped into the water wearing a pink woman’s coat over his underwear. Investigators believed he had an AR-15 rifle in his car trunk, but it was never displayed. No charges were filed.

Last July, Reinking was arrested by the U.S. Secret Service after he crossed into a restricted area near the White House and refused to leave, saying he wanted to meet President Donald Trump. Reinking was not armed at the time, but at the FBI’s request, state police in Illinois revoked his state firearms card and seized four guns from him, authorities said.

The AR-15 used in the shootings was among the firearms seized.

Then, in August, Reinking told police he wanted to file a report about 20 to 30 people tapping into his computer and phone and people “barking like dogs” outside his residence, according to a report.

Reinking agreed to go to a local hospital for an evaluation after repeatedly resisting the request, the report said.

“There’s certainly evidence that there’s some sort of mental health issues involved,” Tazwell County Sheriff Robert Huston said. But he said deputies returned the guns to Reinking’s father on the promise that he would “keep the weapons secure and out of the possession of Travis.”

Nashville Police spokesman Don Aaron said that Reinking’s father “has now acknowledged giving them back” to his son.

After the shooting, police recovered three of the four guns originally taken from Reinking, officials said. They believe he still has at least one handgun.

Phone calls to a number listed for the father, Jeffrey Reinking, went unanswered.

It is not clear why Reinking moved recently from Morton, Illinois, to Nashville and if it had anything to do with being near Swift. Police say he was employed in construction for a while, and there would have been enough work in the booming city for him.

Police say Reinking drove into the Waffle House parking lot in his gold Chevy Silverado pickup early Sunday and sat there for about four minutes before opening fire outside the restaurant.

The victims fatally shot in the parking have been identified as Taurean Sanderlin, 29, of Goodlettsville, and Joe Perez, 20, of Nashville.

Sanderlin was an employee at the restaurant.

Perez’s mother posted a picture of her son on Facebook and asked for prayers, saying it was the hardest day of her life. “Me, my husband and sons are broken right now with this loss,” Trisha Perez said in the post. “Our lives are shattered.”

Reinking then went inside the restaurant and opened fire, police said.

One of the fatally wounded inside was DeEbony Groves, a 21-year student at Nashville’s Belmont University. She was remembered as an exceptional student who made the Dean’s list, and a tenacious basketball player.

“She was a brilliant young lady, very, very intelligent and a very hard worker,” Gallatin High School basketball coach Kim Kendrick told The Tennessean.

Akilah Dasilva was also killed inside the restaurant. The 23-year-old from Antioch was a rap artist and music video producer who had such skills behind the camera that he was a favorite among many of Music City’s independent musicians and recording labels, The Tennessean reported.

“Music is my life and I will never stop until I achieve my dreams,” Dasilva said on his Twitter account.

Dasilva’s mother told CBS News that her son was a student at Middle Tennessee State University and aspired to be a music engineer.

He was at the restaurant with his girlfriend, 21-year-old Tia Waggoner, the paper reported. Waggoner was wounded and is being treated at Vanderbilt University Medical Center. Dasilva’s family said she underwent surgery and doctors were trying to save her leg.

Police say Sharita Henderson, 24, of Antioch, was wounded and is being treated at VUMC.

Also wounded was James Shaw Jr., a 29-year-old restaurant patron who burned his hand grabbing the hot muzzle of the assault weapon as he wrestled the gun away. A Nashville native who works as a wireless technician for AT&T, Shaw said he was no hero — despite being hailed as one by Nashville Mayor David Briley.

Shaw said he pounced on the suspect out of self-preservation, after making up his mind that “he was going to have to work to kill me.”