BUFFALO, N.Y. (AP) — The white gunman who killed 10 Black people at a Buffalo supermarket pleaded not guilty Thursday to hate-motivated domestic terrorism and other charges as a prosecutor called the evidence against him overwhelming.

A lawyer entered the plea for Payton Gendron, 18, who didn't speak during a brief hearing with a heavy security presence.

Witnesses, police and Gendron's own writings and livestreamed video incriminated him as the gunman who used an AR-style semi-automatic rifle to target shoppers and employees of a Tops Friendly Market, which authorities said he chose because of its location in a predominantly Black neighborhood. All 10 people killed in the May 14 assault were Black.

“There is overwhelming proof of the defendant’s guilt,” Assistant District Attorney John Fereleto said. “The defendant was caught at the scene of the crime with the weapon in his hands.”

Gendron has been held without bail since the shooting and is due back in court July 7.

He was charged with murder shortly after the attack. On Wednesday, a new indictment expanded the case to include a domestic terrorism charge that carries the potential for an automatic life sentence, along with 10 counts of first-degree murder, 10 counts of second-degree murder as a hate crime, criminal possession of a weapon and three counts of attempted murder as a hate crime.

“When you hear the phase ‘throw the book at’ someone, well, in this case right here, the defendant just got ‘War and Peace,’" District Attorney John Flynn said at a news conference after the arraignment.

The domestic terrorism hate crime charge — officially, domestic acts of terrorism motivated by hate in the first degree — was added to state law just two years ago, after a mass shooting targeting Mexicans at a Walmart store in El Paso, Texas. In Gendron's case, the charge accuses him of killing at least five people “because of the perceived race and/or color” of his victims.

Outside court, Buffalo Mayor Byron Brown called Gendron “a racist, hate-filled outsider who came to our community with the stated intent to kill as many Black people as possible.”

Prosecutors said Gendron drove about three hours to Buffalo from his home in Conklin, New York, to target African Americans. Shortly before opening fire, he posted documents that outlined his white supremacist views and revealed he had been planning the attack for months.

Federal authorities also are investigating the possibility of hate crime charges against Gendron.

The slain victims ranged in age from 32 to 86. Three other people were wounded.

The bloodshed, followed 10 days later by a mass shooting that killed 19 children and two teachers inside an elementary school in Uvalde, Texas, has renewed a national debate about gun control.

Meanwhile, a 911 dispatcher was fired Thursday after being accused by a Tops employee of hanging up on her during the rampage. The dispatcher, who was put on administrative leave two days after the shooting, was terminated after a disciplinary hearing Thursday, Erie County spokesperson Daniel Meyer said.

A message seeking comment was sent Thursday to a spokesperson for the dispatcher's union. The dispatcher told The Buffalo News late last month that she was sorry about what the caller went through during the shooting, adding that more facts would come out at the hearing.