A grand jury has indicted the accused gunman in the Buffalo, New York, grocery store shooting that left 10 dead and three others wounded on a first-degree murder charge.

Payton Gendron, 18, appeared briefly in court Thursday. Assistant district attorney Gary Hackbush said the indictment was handed up Wednesday.

Gendron, wearing orange clothing and mask, was silent throughout the proceeding and sent back to jail. Someone shouted "Payton you’re a coward!" as he was led out.

Ten people were killed, and three others wounded in the Saturday shooting at the Tops Friendly Market in a predominantly Black neighborhood of Buffalo. Authorities said 11 out of the total 13 people shot were Black. Gendron, who is White, allegedly posted a manifesto hundreds of pages long online hours before the shooting detailing his infatuation with the White supremacy ideology.

Authorities are continuing to investigate the possibility of hate crime and terrorism charges.

In New York, prosecutors can charge a defendant with first-degree murder only under special circumstances, including when multiple people are killed in a single incident, like in the Buffalo shooting. The single count against Gendron covers all 10 deaths at the supermarket.

New York Gov. Kathy Hochul on Wednesday authorized the state’s attorney general, Letitia James, to investigate social media platforms used by Gendron to determine if they were liable for "providing a platform to plan and promote violence."