A half-naked man suspected of fatally shooting four people at a Tennessee Waffle House remains on the run, and may be armed with one of the guns seized from him last year after he tried to enter the White House to see Donald Trump.

More than 80 Nashville police officers continue to search for Travis Reinking, 29, alongside agents with the FBI, the US 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 car park and then stormed the restaurant, police said.

Four people were killed and four others were injured before quick-thinking customer James Shaw Jr wrestled the assault weapon away, preventing more bloodshed.

Metropolitan Nashville police chief Steve Anderson said Reinking was last seen on Sunday around a wooded area near an apartment complex where he lived, wearing only trousers and no shirt or shoes.

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

At least four people died after a gunman opened fire at the restaurant in Nashville (Mark Humphrey/AP)
At least four people died after a gunman opened fire at the restaurant in Nashville (Mark Humphrey/AP)

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

The police chief added: “He’s on foot. 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. Neighbours should check on each other.”

Nashville public schools will go into “lock-out” mode if Reinking is not found in time for classes starting on 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 on 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 US 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.

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

Mr Sanderlin was an employee at the restaurant.

One of those 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.

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 favourite among many of Music City’s independent musicians and recording labels, The Tennessean reported.