CNN  — 

Details continue to emerge about the May 14 shooting at a Buffalo, New York, supermarket and the 18-year-old who authorities say is responsible.

Thirteen people – 11 of whom are African American – were shot, according to city officials, who have said the massacre was racially motivated, pointing in part to racist writing purportedly by the suspect. Ten were killed, while three victims suffered non-life-threatening injuries.

The suspect – identified as Payton S. Gendron, an 18-year-old White man – surrendered to police. He pleaded not guilty to a charge of first-degree murder later that day, per Buffalo City Court Chief Judge Craig Hannah. Erie County District Attorney John Flynn said he expected to file additional charges.

On June 1, a grand jury returned a 25 count indictment against Gendron. He is facing 10 counts of first-degree murder, 10 counts of second-degree murder as a hate crime and three counts of attempted murder as a hate crime, according to court documents. Gendron is also facing a charge of domestic terror and a weapons charge, court documents state.

Gendron pleaded not guilty to the indictment, his attorney said in court Thursday afternoon.

The FBI is investigating the shooting as both a hate crime and a case of racially motivated violent extremism, said Stephen Belongia, FBI special agent in charge of the Buffalo field office.

Federal prosecutors are also working to bring charges against Gendron, law enforcement officials say.

Here’s what we know about the shooting and the investigation.

How the shooting unfolded

When the suspect arrived at the Tops Friendly Markets on Jefferson Avenue about 2:30 p.m., he was “very heavily armed,” according to Buffalo Police Commissioner Joseph Gramaglia.

“He had tactical gear, he had a tactical helmet on, he had a camera that he was livestreaming what he was doing.”

The suspect first opened fire in the store’s parking lot, authorities said, shooting four people. Three of those people died, Gramaglia said.

The suspect went inside the store and began shooting customers, police said. A security guard inside the store who was a retired Buffalo police officer shot the suspect. But because the suspect wore heavy armor, the bullets did not have any effect, Gramaglia said.

The suspect shot and killed the security guard and continued working his way through the store, the commissioner said. When police arrived, the suspect put his gun to his neck but later dropped the gun and took off some of his gear, he added.

He surrendered and was transported to Buffalo police headquarters.

Police speak to bystanders after the shooting at a supermarket on May 14, 2022, in Buffalo, New York.

During his arrest, the suspect made very disturbing statements describing his motive and state of mind following his arrest, according to an official familiar with the investigation. The alleged shooter made it known he was targeting the Black community during the statements, according to the official.

Warrants are being obtained for suspect’s home, vehicle, social media platforms, computer, telephone, and any other digital technologies, Gramaglia said. The investigation shows Gendron acted on his own in the shooting, he added.

What we know about the victims

Of the 13 people shot, 11 are African American and two are White, said Gramaglia.

Four were store employees, he said. Three suffered “nonfatal wounds,” he said. The fourth, security guard Aaron Salter, a retired Buffalo police lieutenant, was killed as he tried to stop the suspect. Mayor Byron Brown called him a “hero, who tried to protect people in the store, tried to save lives, and in the process, lost his own life.”