More details emerged Sunday after a white teenaged gunman shot and killed 10 people and wounded three others Saturday afternoon at a supermarket in east Buffalo, New York.

Police said suspect Payton S. Gendron, 18, was motivated by hate to shoot up Tops Friendly Market in a predominantly Black neighborhood. Eleven of the 13 people shot were Black, officials said.

Gendron, who was armed with an assault weapon and wore body armor, opened fire in the parking lot and inside the store, shooting four employees, according to authorities. He eventually surrendered to the police.

The gunman drove over three hours from his small town to the neighborhood in Buffalo.

“It was a straight up racially motivated hate crime,” said Erie County Sheriff John Garcia.

The Associated Press reported Sunday that a law official said the alleged gunman had threatened a shooting at his high school in 2021 and had been sent for mental health treatment.

The shooting is being investigated as a hate crime and "an act of racially-motivated violent extremism," Attorney General Merrick Garland said. President Joe Biden released a statement late Saturday about the shooting.

“Any act of domestic terrorism, including an act perpetrated in the name of a repugnant white nationalist ideology, is antithetical to everything we stand for in America,” Biden said. “Hate must have no safe harbor.”

Gendron was charged with first-degree murder. He has pleaded guilty and is currently being held without bail, Erie County District Attorney John J. Flynn said in a press release. If found guilty, Gendron faces a life sentence without the possibility of parole.

The suspected shooter arrived at the grocery store around 2:30 p.m., dressed in heavy tactical gear, police said. He also wore a helmet with a camera attached to it and live-streamed the shooting on Twitch, the streaming platform confirmed on Saturday.

Police are trying to confirm whether Gendron had a 180-page document that claims that white Americans are at risk of being replaced by Black people. The Buffalo News reported Saturday that Gendron's semi-automatic gun had “the N-word” spelled out in white paint on the barrel. Also on the gun was No. 14, which is a reference to a popular white supremacist slogan.

In a news conference Saturday, Gov. Kathy Hochul called the shooting an “act of barbarism” and “white supremacist terrorism” along with an “execution of innocent human beings.”