Prosecutors say the teens were involved in the fight on September 16 in Nassau County, which left Khaseen Morris dead — a 16-year-old student at Oceanside High School. They were arrested on Friday.

Earlier this week, Tyler Flach, aged 18, of Lido Beach, L.I., was charged with second degree murder. He is being held without bail.

Police said between 50 and 70 teenagers watched the bloody fight, and several recorded the fight on cell phones, doing nothing to help Morris.

The victim’s sister told Newsday she was comforted by the additional arrests.

“People can’t do this to someone so good and they think there will be no justice whatsoever,” Keyanna Morris, 30, told the newspaper.

Among those arrested were Haakim Mechan, 19, Marquis Stephens, 18, Javonte Neals, 18, Taj Woodruff, 17, and Taj Woodruff, 17, and Sean Merritt, 17, all in Long Beach.

They all pleaded not guilty to the high school gang attack on their Saturday accusation in Hempstead.

Two 16-year-olds were also charged with gang aggression but were not identified by police because of their age. Scott Gross, a lawyer for one of the 16-year-olds, said his client “had no role” in the murder.

Detective Lieutenant Stephen Fitzpatrick told a news conference on Saturday that the fight at a mall near Oceanside High School began because Morris was with the ex-girlfriend of one of the suspects.

Fitzpatrick said all suspects participated in the attack on Morris.

“Each of them played an active role,” he said. “They came with the intention of seriously hurting you. Khaseen was killed as a result.

“It’s the first step toward justice,” Fitzpatrick said about the arrests, according to WPIX-TV.

Morris’s funeral was being held on Saturday.

Long Island, Assault, Javonte Neals, WPIX-TV, Nassau County