Ten people have been killed in a shooting in New York state that is being investigated as a racially-motivated hate crime.
An 18-year-old man was detained after a stand-off at the scene in the city of Buffalo. Police have not named him.
The suspect entered a busy supermarket on Saturday afternoon before opening fire. He used a camera to stream the attack online, police said.
The FBI described the shooting as an act of “violent extremism”.
“We are investigating this incident as both a hate crime and a case of racially-motivated violent extremism,” Stephen Belongia, the agent in charge of the FBI’s Buffalo office, told a news conference.
The suspect is believed to have driven for several hours to reach the predominantly black area of the city. Thirteen people were shot and the majority of the victims were black, Buffalo Police Commissioner Joseph Gramaglia said.
The three wounded victims – who all worked at the supermarket – have not sustained life-threatening injuries.
A retired police officer who was working as a security guard at the supermarket tried to shoot the suspect but was among those killed.
The suspect was carrying a high-powered rifle and wore body armour as well as a helmet, police said. He surrendered his weapon after a tense stand-off before being detained.
He has since been charged in court with first-degree murder and will appear in court on Saturday, Erie County District Attorney John Flynn later said. He added that further charges may still be brought.
Speaking to CBS, a police source alleged that the man had shouted racial slurs during the attack.
“This is the worst nightmare that any community can face and we are hurting, we are seething right now,” Buffalo Mayor Byron Brown told reporters at a news conference.
“We cannot let this hateful person divide our community or our country,” he added.
Grady Lewis, who witnessed the attack from across the street, told local media he saw the man open fire. “I saw the guy go in, army-style, bent over, just shooting at people,” he said.
Shonnell Harris, who was working in the shop during the attack, told Buffalo News that she heard more than 70 shots as she ran to escape the building through a backdoor.
“The store was full. It was the weekend,” she said. “It feels like a nightmare.”
Describing the aftermath of the attack, one police officer told Buffalo News: “It’s like walking onto a horror movie, but everything is real. It is Armageddon-like”.
Later on Saturday, New York Governor Kathy Hochul said the suspect was a “white supremacist who has engaged in an act of terrorism”.
This was “a military style execution targeting people who simply wanted to buy groceries in a neighbourhood store,” she said while visiting Buffalo.
US President Joe Biden, meanwhile, has been briefed on the shooting. “The president and the first lady are praying for those who have been lost and for their loved ones,” a White House statement said.