A heavily armed 18-year-old man shot 10 people dead on May 14 at a Buffalo, New York grocery store in a “racially motivated” attack that he live-streamed on camera, authorities said.

The gunman, who was wearing body armor and a helmet, was arrested after the massacre, Buffalo Police Commissioner Joseph Gramaglia told a news conference.

Gramaglia put the toll at 10 dead and three wounded. Eleven of the victims were African Americans.

The gunman shot four people in the parking lot of the Tops supermarket, three of them fatally, then went inside and continued firing, Gramaglia said.

Among those killed inside the store was a retired police officer working as an armed security guard.

The guard “engaged the suspect, fired multiple shots,” but the gunman shot him, Gramaglia told reporters.

When police arrived, the shooter put the gun to his neck, but was talked down and surrendered, he added.

Stephen Belongia, special agent in charge of the FBI’s Buffalo field office, told the news conference that the shooting is being investigated as a hate crime.

“We are investigating this incident as both a hate crime and a case of racially motivated violent extremism,” Belongia said.

Erie County Sheriff John Garcia described the attack as “pure evil.”

“It was straight up racially motivated hate crime from somebody outside of our community,” he said.

John Flynn, the district attorney for Erie County, where Buffalo is located, said the shooter used an “assault weapon” – a term that can apply to types of rifles and shotguns in New York – but did not specify which kind.

Flynn’s office said in a tweet Saturday night that the suspect – identified as Payton Gendron of Conklin, New York – had been arraigned on a charge of first degree murder, which carries a sentence of life without parole. He is being held without bail.

Asked during the earlier press conference if the shooter could face the death penalty on the federal level, the US attorney for the Western District of New York, Trini Ross, said: “All options are on the table as we go forward with the investigation.”