The suspect in the supermarket shooting in Buffalo, New York, that left 10 dead is an 18-year-old who previously threatened violence against his high school, authorities said.

Payton Gendron of Conklin, New York, drove more than three hours to a grocery store Saturday and shot 13 people, killing 10. Authorities believe the assault was an intentional attack on members of a predominantly Black upstate New York neighborhood.

Eleven of the 13 people who were shot were Black.

Gendron was identified in the deadly attack Saturday and was charged with one count of murder. Officials said they would weigh additional charges in the coming days. 

Meanwhile, federal agents on Sunday were working to confirm the authenticity of a 180-page racist manifesto that was posted online and identified Gendron by name as the gunman, a law enforcement official told The Associated Press on Sunday.

Here's what we know about the suspect: 

Suspect had previously threatened his high school

Gendron threatened an attack at his high school last year, resulting in a referral for a mental health evaluation, a law enforcement official told USA TODAY on Sunday. The incident was reviewed by state authorities at the time.

The official, who was not authorized to comment publicly, said the suspect's parents were cooperating with authorities.

New York State Police said troopers were called to the Conklin school last June for a report that the then 17-year-old student had made threatening statements. He spent a day and a half at the hospital before being released, authorities said, and then had no further contact with law enforcement.

Gendron graduated from the Susquehanna Valley Central School District in Conklin, New York, in 2021. District officials declined to comment on the  suspect's ties to the school, “in light of the extremely sensitive nature of this matter.”

More than 95% of Conklin’s 5,000 residents are white, according to 2020 census data. Black residents comprise about 0.6% of the town’s population.

According to the manifesto that Gendron allegedly wrote, which has not yet been confirmed by authorities as authentic, he was enrolled in the engineering sciences program at SUNY Broome Community College.

SUNY Broome officials confirmed in a statement to USA TODAY that Gendron was enrolled at the community college as a full-time student for the Fall 2021 and Spring 2022 semesters.

"The individual was enrolled through March 22, 2022, and has not been enrolled at SUNY Broome since that date," the statement said. 

What was the suspect's motive?

Early investigations point to a racist motive in the killings.

“This individual came here with the express purpose of taking as many Black lives as he could,” Buffalo Mayor Byron Brown said at a news conference Sunday.

Rep. Brian Higgins, D-N.Y., a Buffalo native, said the evidence gathered points to an “explicit act of racially motivated violence.” Citing briefings with law enforcement officials, Higgins said the suspect carried an assault weapon inscribed with a racial epithet.

“I was on site for the last three hours, and I listened carefully to what the FBI, police, the district attorney and the U.S. attorney had to say,” Higgins told USA TODAY. “There is no doubt this was a racially motivated attack.”

He said authorities were reviewing a graphic manifesto that referenced other racially motivated attackers, including an avowed white supremacist who killed nine people in 2015 at a Black church in Charleston, South Carolina. 

The manifesto, which focuses on racist, anti-immigrant and antisemitic beliefs, detailed the plot and identified Gendron by name as the gunman, a law enforcement official told The Associated Press on Sunday. The official was not authorized to publicly discuss details of the investigation and spoke to AP on condition of anonymity.

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How did the shooter obtain the gun?

New York Gov. Kathy Hochul said the suspect acquired the rifle used in the attack legally but the weapon had been modified with illegal magazines. New York bars the sale of any magazine that has a capacity of more than 10 rounds.

She said law enforcement was working to determine where the magazines were acquired but noted they could be purchased as close as Pennsylvania. She didn't elaborate on how many bullets the magazines were able to hold.

Gendron also wore tactical gear, including body armor, as he assaulted the grocery store.

Suspect arraigned on murder charge

Gendron was arraigned Saturday evening before Buffalo City Court Judge Craig Hannah on one count of first-degree murder.

Hannah ordered that Gendron be held without bail. He will return to court for a felony hearing Thursday morning.

Officials said they will weigh additional charges in the coming days. Gendron's attorney, Brian Parker, requested that his client undergo a psychiatric examination.