A nude gunman has killed four people at a Waffle House in Nashville in the US state of Tennessee, police say.
The man burst into the restaurant at 03:25 (08:25 GMT) in the suburb of Antioch and opened fire with a semi-automatic rifle.
Two other people were wounded. One of them wrestled the weapon from the man, who then fled the scene on foot.
Police are hunting for the suspect, whom they identified as Travis Reinking, 29, from Illinois.
James Shaw Jr, the customer credited with saving lives by taking the gun off the killer, has told US media he does not feel like a hero because "it feels selfish".
How did the attack unfold?
Arriving in a pick-up truck, the killer shot two people outside the restaurant, before firing more shots inside, Nashville police spokesman Don Aaron said.
Three victims died at the scene and the fourth in hospital.
Police say he was naked except for a green jacket, which he shed as he left the scene.
The suspect was later spotted in woodland wearing black trousers but no shirt, police say.
Police released a photo of the rifle taken off him in the restaurant, which appears to be an AR-15, a weapon commonly used by mass shooters in the US.
Similar rifles were used in the Las Vegas shooting last October that killed 58 people, and the Florida school attack in February that left 17 students and staff dead.
Debate over gun control intensified following the Florida shooting, with mass protests and school walkouts across the country demanding stricter legislation in recent weeks.
How did Shaw intervene?
At the start of the shooting, the customer ran to the restaurant's toilet area, Aaron said.
When the firing stopped and the gunman was looking at his weapon, Shaw rushed him, wresting the rifle from his hands and tossing it over the counter.
Grazed by a bullet himself, the 29-year-old said later he had simply seen his chance and taken it, the Tennessean reports.
"I remember I was like 'Dang, I'm basically in a barrel'," he said. "There is no place for me to go."
"I... remember thinking that he is going to have to work for this kill," he continued. "I had a chance to stop him and thankfully I stopped him."
"I grabbed the gun and kept it down," Shaw said. "He had one hand on it. I pulled it away and threw it over the bar."
While being treated in hospital for his injury, he was told by a girl that he had saved her life.
"I didn't do it to be [a] hero," Shaw said.