Nathaniel D. Simms, who admitted to shooting an AK-47-style assault rifle into a crowd of mourners and to taking part in the killing of five people, was sentenced to 25 years in prison Friday. It was the minimum term allowable under mandatory D.C. sentencing guidelines.

Simms, 28, of Capitol Heights, was one of six men convicted in the March 2010 attacks, part of the District’s deadliest outbreak of violence in decades. He was the only one to plead guilty to a role in the shootings, and his information and testimony aided authorities in their prosecution of the other five.

Simms faced a maximum of 40 years for each murder. D.C. Superior Court Judge Michael L. Rankin accepted the prosecution’s recommended sentence, 60 years with all but 25 years suspended, during a hearing Friday. Simms was credited for two years of time already served, and must serve at least 85 percent of the remaining 23 years before being eligible for early release.

Rankin said he acknowledged Simms’s remorse and hoped the sentence might encourage others to admit their crimes and cooperate with authorities, perhaps helping to combat a “stop snitching” mentality.

The judge said he hoped the sentence might encourage people who might not want to take responsibility for crimes or testify against others.

“If we don’t change that view, we will go back to days before we call ourselves a civilized nation,” the judge said.

The sentencing is a sort of bookend to the shootings that left five people dead and eight wounded over eight days in March 2010.

In pleading guilty, Simms agreed to detail his role in the shootings and testify against his five friends and co-conspirators. During a trial earlier this year, he described how, on March 30, 2010, he pointed the assault rifle out of a rented minivan’s passenger-side window and fired into a crowd. Some of those he hit had attended the funeral of Jordan Howe, 20, earlier that day; the shooting of Howe, eight days earlier, started the run of deadly violence.

The other five men involved in the shootings — Jeffrey Best and Robert Bost, both 23; Orlando Carter, 22, and his brother Sanquan Carter, 21; and Lamar Williams, 24 — were convicted of multiple counts of murder and sentenced in September. Best, Bost and Carter were sentenced to life in prison without the possibility of parole. Sanquan Carter was sentenced to 54 years, and Williams — who was not present at the shootings but provided weapons — received a 30-year sentence.

Before Rankin announced his sentence, Simms apologized to the victims’ family members — as he did during the three-month spring trial of the other five men.

“I wish I could bring your loved ones back,” Simms said, his voice cracking at times. “I pray you see through your pain that my apology is sincere.

“I’m sorry,” he said. “I pray every night, but I feel like God doesn’t forgive murderers.”

Members of Simms’s family sat among those of the victims in the crowded courtroom. When marshals escorted Simms in, his mother bowed her head and began crying from a front-row seat.

During the hearing, assistant U.S. attorneys Michael Brittin and Bruce Hegyi spent more than an hour outlining how “critical” Simms’s cooperation was to their case. The prosecutors reiterated their recent memo, telling Rankin that Simms initiated the conversation about his cooperation just days after his arrest and outlined the involvement of all six shooters, including himself.

Prosecutors also said Simms identified the reason the shootings begain: Sanquan Carter’s belief that someone at a party on March 22 had stolen his bracelet, which led him to call his brother and friends to the scene and fire the first shots. Howe was killed in that shooting.

“He provided the answers the city needed,” Brittin said.

Athough all five killers have been convicted, Brittin added Friday, additional charges could be pending against others who played a role in the shootings. He did not elaborate.

In a statement before Rankin, Nardyne Jefferies displayed ­poster-size photos of her daughter, Brishell Jones, 16, the youngest victim of the shootings, to Simms and the audience. She then held up an autopsy photo of her daughter, of similar size.

The sentence angered Jefferies and other victims’ family members, some of whom walked out of the courtroom after it was announced. In a hallway after the hearing, Simms’s sister confronted Jefferies, telling her that her brother was “not a killer” and had “no choice” but to go along with the shootings or risk being killed himself.

Rankin also sentenced Simms to five years of probation following his release and ordered him to pay $5,000 of his prison pay to a victims compensation fund. The judge then offered Simms some advice.

“If you believe your God doesn’t forgive you, then you’re praying to the wrong God,” he said. “My God forgives.”

Simms nodded his head.