A white gunman dressed in military-style clothing allegedly killed 10 people and injured three others on Saturday at a grocery store in a predominately Black neighborhood in Buffalo, N.Y., authorities say.
The suspect, who is 18, has been charged with first-degree murder. Officials say they are investigating the attack as a racially motivated hate crime and are considering a terrorism charge.
The FBI is separately investigating the incident as a hate crime and racially motivated violent extremism.
Here's what we know about the suspect.
He previously threatened to attack his high school
The suspected shooter threatened his high school in Conklin, N.Y. in June of last year. Authorities say the threat was general, and did not outline specific people or a place.
"The state police responded. They investigated. They interviewed the subject. And they felt at the time it was appropriate to have that individual brought in for a mental health evaluation," said Buffalo police commissioner Joseph Gramaglia at a press conference Sunday.
The suspected gunman was released after a day and a half in the hospital.
He livestreamed the attack
The alleged gunman livestreamed the shooting on Twitch, an interactive content streaming service. Twitch said the original stream was removed less than two minutes after the attack began.
Twitch suspended the suspected shooter from the platform indefinitely.
Footage of the shooting circulated online after Twitch took down the video. A minute-long clip posted on Facebook was taken down because it violated the platform's community standards.
After amassing thousands of views, a similar clip on Twitter was taken down for violating the company's terms of service.
He left behind a racist screed
Writings authored by someone whose name matched that of the suspected shooter were posted to anonymous message board 4chan. The alleged shooter cites "extreme boredom" as a catalyst to his radicalization.
In the 180-page document, the shooter references "the great replacement," which is a white supremacist conspiracy theory that claims people of color are being brought into the U.S. and other Western countries to overtake and "replace" white voters in the name of a political agenda.
The Anti-Defamation League says white supremacists blame Jews for nonwhite immigration to the U.S.
The gunman who killed 51 people in New Zealand mosques in 2019 believed in the same theory. The suspected shooter at the Buffalo grocery store said the gunman in New Zealand was an inspiration.
He wore tactical gear and police recovered weaponry in his car
The suspected shooter wore body armor and military-style clothing during the attack.
Aaron Salter, a security guard at the grocery store, fired at the suspected shooter, but the bullet didn't break through the suspect's armor. Salter is among those killed in the attack.
The suspected gunman used a Bushmaster AR-15 style assault rifle to carry out the attack at the Tops supermarket. Police recovered another rifle and a shotgun in his car.