Travis Reinking sits in a police car after being arrested in Nashville, Tenn., on Monday. Police said Reinking opened fire at a Waffle House early Sunday, killing at least four people.

NASHVILLE, Tenn. — The mentally unstable gunman suspected of killing four people in a late-night shooting at a Waffle House restaurant was arrested near his apartment Monday after hiding from police for more than a day, authorities said.

Police and federal agents had mounted a massive manhunt for 29-year-old Travis Reinking after the Sunday morning attacks, in which a gunman clad only in a jacket used an assault rifle to attack a diverse crowd of patrons at the restaurant before being disarmed by a patron.

Construction workers told officers Monday that a person matching Reinking’s description walked into the woods near a construction site, Lt. Carlos Lara told reporters. A detective spotted Reinking, who lay down on the ground to be handcuffed when confronted, Lara said.

Reinking carried a black backpack with a silver semi-automatic weapon and .45-caliber ammunition, Lara said. Detectives cut the backpack off him.

Police spokesman Don Aaron said Reinking requested a lawyer and was taken to a hospital before he would be booked on four counts of criminal homicide. It’s not clear why Reinking attacked shortly after 3 a.m. Sunday, though he may have “mental issues,” Metropolitan Nashville Police Chief Steve Anderson said earlier.

Police said Reinking opened fire in the restaurant parking lot before storming the restaurant, which had about 20 people inside. Four people — three of them black and one Hispanic — were killed and four others injured before a customer wrestled the weapon away and Reinking, who is white, ran out, police said.

Police said Reinking stole a BMW days before the attack. The car was quickly recovered, but authorities did not immediately link the theft to Reinking.

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

In 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.

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

Another sheriff’s report said Reinking barged into a pool in Tremont, Ill., 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 entered a restricted area near the White House and refused to leave, saying he wanted to meet President Donald Trump. Reinking was not armed, but at the FBI’s request, Illinois police revoked his state firearms card and seized four guns from him, authorities said.

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

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.

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