NASHVILLE, Tenn. -- As an intense manhunt continues for the suspect in a Waffle House restaurant shooting that killed four people, police are warning residents of a Nashville neighborhood to beware of the alleged killer. More than 80 Nashville police officers continued to search for Travis Reinking early Monday, authorities said.

Agents with the FBI, the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives and troopers with the Tennessee Highway Patrol were also assisting in the manhunt as disturbing reports about the wanted man's past behavior came to light.

He was also added to the Tennessee Bureau of Investigation's Top 10 Most Wanted list.

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Nashville police tweeted an update Monday morning:

MNPD officers, to include SWAT, have continued the search for Travis Reinking in the Antioch area overnight. There have been no credible sightings. The search will continue. All schools in the area have been cleared by officers. He was last seen Sun morn behind his apt complex. pic.twitter.com/ChY1ihCdKG — Metro Nashville PD (@MNPDNashville) April 23, 2018

Reinking was nearly naked, wearing only a green jacket and brandishing an assault-style rifle when he opened fire in the parking lot, then stormed the restaurant, police say. In addition to the four people killed, four were wounded.

Police credit a quick-thinking customer who wrestled the gun away from the suspect for preventing more loss of life.

James Shaw Jr., a 29-year-old restaurant patron, suffered minor wounds during the encounter, police said.

Shaw, a Nashville native who works as a wireless technician for AT&T, said he was no hero - despite being hailed as one by Nashville Mayor David Briley.

Shaw said he saw pounced on the suspect after making up his mind that "he was going to have to work to kill me."

A reporter for CBS Nashville affiliate WYVF-TV tweeted about Shaw:

Hero (noun): a person who is admired for courage, or noble qualities. Thank you James Shaw. You were truly a hero today. pic.twitter.com/YRMO2eUJ6H — Chris Conte (@chrisconte) April 22, 2018

He also admitted, "I didn't really fight that man to save everyone else. That may not be a popular thing. I took the gun so I could get myself out" of the situation. But he said he was glad he saved others, as well.

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. Authorities said Reinking could be armed and weren't ruling out that he had left the area. He was believed to be wearing only pants and no shirt or shoes.

Anderson said there was no clear motive, though Reinking may have "mental issues." He may still be armed, Anderson told a mid-afternoon news conference, because he was known to have owned a handgun that authorities have not recovered.

"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."

Officials with the Nashville public school system say schools will go into "lock-out" mode if Reinking isn't found in time for class Monday. During the lock-out, students will be free to move about school buildings but no guests or visitors will be allowed in.

The search continued as police reports from Illinois portrayed Reinking as a disturbed man with paranoid delusions, and one who liked firearms.

Congressman calls for gun control in wake of Waffle House shooting

The reports were among multiple past red flags about the suspect, who had just recently moved to Nashville from Morton, Illinois.

Reinking was arrested by agents of the U.S. Secret Service back in July after he crossed a restricted area near the White House, officials said. He was detained after refusing to leave, saying he wanted to meet President Trump.

In May 2016, deputies from Tazewell County, Illinois, were called to a CVS parking lot. Reinking told officers Taylor Swift was stalking him and hacking his phone, and that his family was also involved, according to a report released Sunday.

It's not clear why Reinking moved to Nashville and if it had anything to do with being near the pop/country superstar. Police say he was employed in construction for a while and there would have been enough work in the booming city for him.

In August, after the White House incident, Reinking told police in Tazewell County, Illinois, that he wanted to file a report about 20 to 30 people tapping into his computer and phone. He also complained that people were "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.

Another report from the sheriff's office 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.

Reinking was not armed when he was detained near the White House. However, state police in Illinois, revoked his state firearms card at the request of the FBI and four guns were taken from him, authorities said. The AR-15 used in the shootings was among the firearms seized after U.S. Secret Service agents arrested him last July.

Sheriff Robert Huston in Tazewell County, Illinois, said deputies allowed Reinking's father to take possession of the guns on the promise that he would "keep the weapons secure and out of the possession of Travis." Huston added that, based on deputies' encounters with Reinking, "there's certainly evidence that there's some sort of mental health issues involved."

While Huston said it was unclear how Reinking reclaimed the guns, Nashville Police spokesman Don Aaron said his father "has now acknowledged giving them back."

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

Police recovered three of the four guns that were originally taken from Reinking, officials said. They believe he is armed with at least one handgun.

Reinking, police said, drove into the Waffle House parking lot in his gold Chevy Silverado pickup 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.

Groves was remembered as an exceptional student who made the Dean's list and was 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 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.