Suspect, 18, had mental health check in 2021

The 18-year-old suspect in a racially motivated murderous rampage at a supermarket in a black neighborhood of Buffalo, New York, was held for a mental health evaluation a year ago but released a day later.

The suspect, Payton Gendron, who is white, surrendered to police on Saturday at the grocery store where 10 people were fatally shot. Thirteen people were struck by gunfire－eleven of them black and two white.

Buffalo Police Commissioner Joseph Gramaglia told reporters that Gendron had been taken into custody and given a mental evaluation over 1.5 days in June last year but was released.

In a statement on Sunday, New York state police said they had been called to a high school in Gendron's hometown of Conklin at the Pennsylvania border in June last year, in response to a 17-year-old student making a threat.

Authorities said Gendron drove to Buffalo－the state's second-largest city－from his home several hours away to launch the attack on Saturday, which he broadcast in real time on the social media platform Twitch, a live video service owned by Amazon. The video was taken down less than two minutes after it was posted, the video company said.

"This individual came here with the express purpose of taking as many black lives as he possibly could," said Buffalo Mayor Byron Brown at a news conference on Sunday.

Conklin is more than 370 kilometers southeast of Buffalo.

The suspect opened fire at the Tops grocery store using a gun that he legally purchased, but had an illegally modified, high-capacity magazine.

Gendron bought his assault weapon at a store in Endicott, New York, and said online that he also purchased a shotgun in Pennsylvania, reported The New York Times.

New York Governor Kathy Hochul told ABC News on Sunday that an investigation would focus on what could have been done to stop Gendron, because he had advertised his views online and had been on the authorities' radar.

"I want to know what people knew and when they knew it," she said.

Federal law bars people from owning a gun if a judge determines the person has a "mental defect" or has been placed into a mental institution. An evaluation alone, however, would not bar such a person from acquiring a gun legally.

While the mayor praised the police response, some questioned how the suspect was taken into custody.

"We don't know how the hell he made it out of here alive," said Jeffrey Watkins, motioning toward the Tops Markets parking lot, to the Buffalo News. "If a black person would have had a screwdriver in his hand, he'd have been killed."

"For him to come out of there yesterday… they shouldn't have let him come out like that after he had just killed all of those people," Betty Maclin told the Buffalo News.

US President Joe Biden described the attack on Sunday as a "racially motivated act of white supremacy".

Gendron was arraigned hours after the shooting in state court on first-degree murder charges, which carry a maximum penalty of life in prison without parole, said Erie County District Attorney John Flynn.

Gendron entered a plea of not guilty and is scheduled to return to court on May 19.

Agencies contributed to this story.