Police said he shot 11 Black and two white victims before surrendering to authorities in a rampage he broadcast live on the streaming platform Twitch.
Later, he appeared before a judge in a paper medical gown and was arraigned on a murder charge.
“It is my sincere hope that this individual, this white supremacist who just perpetrated a hate crime on an innocent community, will spend the rest of his days behind bars. And heaven help him in the next world as well,” said Gov. Kathy Hochul, speaking near the scene of the attack.
The massacre sent shockwaves through an unsettled nation gripped with racial tensions, gun violence and a spate of hate crimes. In the day prior to the shooting, Dallas police said they were investigating a series of shootings in Koreatown as hate crimes. The Buffalo attack came just one month after another mass shooting on a Brooklyn subway train wounded 10 people.
The suspected gunman in Saturday’s attack on Tops Friendly Market was identified as Payton Gendron, of Conklin, New York, about 200 miles (320 kilometers) southeast of Buffalo.
It wasn’t immediately clear why Payton had traveled to Buffalo and that particular grocery store. A clip apparently from his Twitch feed, posted on social media, showed Gendron arriving at the supermarket in his car.
The gunman shot four people outside the store, three fatally, said Buffalo Police Commissioner Joseph Gramaglia. Inside the store, security guard Aaron Salter, a retired Buffalo police officer, fired multiple shots. A bullet hit the gunman’s bulletproof armor but had no effect, Gramaglia said.
The gunman then killed the guard, the commissioner said, then stalked through the store shooting other victims.