An 18-year-old white man has shot dead 10 people in a black neighbourhood of New York state in what authorities are calling a racially motivated attack.
The man, named as Payton Gendron in court papers, was arrested after a stand-off at the scene - a supermarket in the city of Buffalo.
The suspect entered the store on Saturday afternoon before opening fire. He livestreamed the attack online.
US President Joe Biden condemned what he called an "abhorrent" act.
"We are investigating this incident as both a hate crime and a case of racially-motivated violent extremism," said Stephen Belongia, from the FBI's Buffalo office, adding there was evidence of "racial animosity."
