Khaseen Morris

(WAND) - A teenager near New York City was stabbed to death while as many as 60 other teens recorded video of the attack instead of helping, police said.

Khaseen Morris, 16, and a friend were jumped by six people Monday in an after-school fight in Oceanside, a Long Island community about 30 miles east of Manhattan.

Morris was stabbed in the chest, and a 17-year-old friend suffered a broken arm and swelling to his head.

Tyler Flach, 18, was arrested Wednesday and charged with murder in connection with the death of Morris, Nassau County police said. He will be arraigned Thursday.

Nassau County Det. Lt. Stephen Fitzpatrick told reporters the attack appears to have started over a fight about a girl and who she was dating or hanging out with.

Investigators said at least 60 teens had gathered to watch the fight, and many took video and posted it on social media.

“Kids stood here and didn’t help Khaseen,” Fitzpatrick said. “They’d rather video. They videoed his death instead of helping him.”

Detectives are asking those kids to come forward now with information.

“If you’re not a part and parcel of the murder of Khaseen Morris, now’s the time to get in touch with us to let us know who did this and why," Fitzgerald said. "If it was just coming here and thinking you were fighting and then he got stabbed during that, you need to get in front of this."

Police said Khaseen, who had just started his senior year at Oceanside High School, walked a girl home from a party on Sunday night. They believe that is what led to his attack and ultimate murder.

"The girl told her ex-boyfriend and said that, 'Oh another boy walked me home,' and she kind of set up this thing to get him jealous," an older sister of Khaseen's told NBC New York.