The man accused of shooting dead 10 Black people at a grocery store in Buffalo, New York, on May 14 has been indicted on 27 federal hate crimes and firearms offenses, the U.S. Justice Department announced on Thursday.

The indictment returned by a federal grand jury tacks on an additional hate crime count against Payton Gendron, 19, in a criminal complaint filed last month. He is now charged with 14 hate crimes violations and 13 firearms offenses.

Authorities say the suspect, who broadcast the attack in real time to the livestreaming service Twitch, is a white supremacist who targeted the store because it was the hub of a tight-knit, predominantly African-American neighborhood in Buffalo.

The indictment spares federal prosecutors the additional legal step of asking a judge to determine whether there is sufficient evidence against the defendant to bring the case to trial.

If convicted, the Conklin, New York, man could face life in prison or the death penalty. Prosecutors must notify the court prior to trial whether they will seek a death sentence.

Gendron, who was 18 at the time of the mass shooting, is currently in state custody facing 10 counts of first-degree murder and 10 counts of second-degree murder in state court.

The indictment came less than an hour before community members planned to gather at the Tops Friendly Markets store - the site of the shooting - for a moment of silence and prayer to commemorate the two-month anniversary of the May 14 attack.

The store, which has since been fully renovated with increased security systems and a victim memorial, is set to reopen on Friday.

Ten days after the massacre, a mass shooting at a school in Uvalde, Texas, left 19 children and two teachers dead. Seven weeks after the Buffalo massacre, seven people where shot dead at a Fourth of July parade in Highland Park, Illinois.

The attacks have reignited a longstanding national debate over U.S. gun laws.

Buffalo Mayor Byron Brown said the Tops store reopening was a step forward in the community's efforts to heal.

"It is important to move forward as a united and strong community. We will not let hate win," he said.

(Reporting by Brendan O'Brien in Chicago and Tyler Clifford in New York; Editing by Josie Kao and Chizu Nomiyama)