The American media reported on Sunday morning that a blind shooting had taken place in the city of "Buffalo" in the state of New York.
New York police say a man who identified himself as a "white supremacist" started shooting at a supermarket.
According to US media reports, at least nine people were shot, according to initial reports, including several who were hit in the head. Two victims died on the ground outside the store and at least one person was taken to a district hospital.
The status of those inside the store is not yet known.
There have been conflicting reports about the shooter's condition, with some media outlets saying he was killed at the scene. Buffalo police, however, said the suspect had been arrested and a semi-automatic rifle confiscated from him.
The assailant broadcast the shooting live on Twitch, showing recorded screenshots of violent scenes, including a woman being shot in the head while walking outside a store.
He also posted a 106-page online statement on the Internet, explaining that his motivation was in part due to a "conspiracy hypothesis" that other races were taking the place of whites. In the document, he says he is 18 years old and describes himself as white and "anti-Semitic."
Minutes later, US media reported, quoting Buffalo police, that at least 10 people had been killed in the shooting.
"Like watching a horror movie, except that everything is real," a Buffalo police official told the media at the scene of the shooting. "It really is an apocalyptic scene!"
An hour later, the New York State Attorney's Office announced that AFBI was treating the incident as a "fanatical crime" and a "violent racist extremism."
Announcing the final statistics, the police said that 13 people were shot in the incident, 10 of whom were killed and 3 were in critical condition.
The White House also said that US President Joe Biden had been informed of the details of the incident and condemned it and expressed his condolences to the families of the victims.