BUFFALO, N.Y. - A white supremacist who killed 10 Black people at a Buffalo supermarket was sentenced to life in prison without parole Wednesday after relatives of his victims confronted him with pain and rage caused by his racist attack.

Anger briefly turned physical at Payton Gendron’s sentencing when a victim’s family member rushed at him from the audience. The man was quickly restrained; prosecutors later said he wouldn’t be charged. The proceeding then resumed with an emotional outpouring from people who lost loved ones or were themselves wounded in the attack.

Mr. Gendron, whose hatred was fueled by racist conspiracy theories he encountered online, cried during some of the testimony and apologized to victims and their families in a brief statement.

Their remarks ranged from sorrow to outrage, shouts to tears. Some vehemently condemned him; others quoted from the Bible or said they were praying for him. Several pointed out that he deliberately attacked a Black community, a three-hour drive from his home in overwhelmingly white Conklin, N.Y.

“You’ve been brainwashed,” Wayne Jones Sr., the only child of victim Celestine Chaney, said as sobs rose from the audience. “You don’t even know Black people that much to hate them. You learned this on the internet.”

“I hope you find it in your heart to apologize to these people, man. You did wrong for no reason,” Mr. Jones said.

Mr. Gendron’s victims at the Tops Friendly Market — the only supermarket and a neighborhood hub on Buffalo’s largely Black East Side — included a church deacon, the grocery store’s guard, a man shopping for a birthday cake, a grandmother of nine and the mother of a former Buffalo fire commissioner. The victims ranged in age from 32 to 86.

Mr. Gendron pleaded guilty in November to crimes including murder and domestic terrorism motivated by hate, a charge that carried an automatic life sentence.

“There can be no mercy for you, no understanding, no second chances,” Judge Susan Eagan said as she sentenced him. She called his rampage “a reckoning” for a nation “founded and built, in part, on white supremacy.”

Mr. Gendron, 19, is due in a federal court Thursday for a status update in a separate case that could carry a death sentence if prosecutors seek it. His attorney said in December that Mr. Gendron is prepared to plead guilty in federal court to avoid execution. New York state does not have the death penalty.

The gunman wore bullet resistant armor and a helmet equipped with a livestreaming camera as he carried out the May 14 attack with a semiautomatic rifle he purchased legally but then modified so he could load it with illegal high-capacity ammunition magazines.

Mr. Gendron was hustled out of a courtroom Wednesday after someone in the audience at his sentencing rushed at him.

“Do I hate you? No. Do I want you to die? No. I want you to stay alive. I want you to think about this every day of your life,” Tamika Harper, a niece of victim Geraldine Talley, told Mr. Gendron. “Think about my family and the other nine families that you’ve destroyed forever.”

Mr. Gendron locked eyes with Ms. Harper as she gently spoke. Then he lowered his head and wept.

Minutes later, Barbara Massey Mapps excoriated him for killing her 72-year- old sister, Katherine Massey, a neighborhood activist. As Mrs. Mapps shouted and pointed at Mr. Gendron, a person in the audience took a few steps toward him before getting held back.

“You don’t know what we’re going through,” a man shouted as he was led away by court officers. For several minutes thereafter, family members hugged and calmed