A Long Island teen was fatally stabbed at a strip mall near his high school as dozens of other students pulled out their cellphones to record the melee rather than help him, police said.

Khaseen Morris, a 16-year-old senior at Oceanside High School, was stabbed once in the chest Monday afternoon during an apparent dispute over a girl. He later died at a hospital after many of the 50 to 70 teens who gathered nearby recorded the bloody attack and made no attempt to stop it, Nassau County police said at a news conference Tuesday.

“Kids stood there and didn’t help Khaseen,” Detective Lt. Stephen Fitzpatrick told reporters, according to Newsday. “They’d rather video. They videoed his death instead of helping him.”

Police are now looking for six to seven teens thought to have been involved in the attack after interviewing witnesses and reviewing footage posted on social media, including on Snapchat, as well as surveillance video from the nearby strip mall, Fitzpatrick said.

Morris, who was not armed during the stabbing, knew that the ex-boyfriend of a girl he walked home from a party on Sunday had been trying to find him to confront the teen, according to police.

Fitzpatrick called on those at the scene of the fatal attack to share what they know with detectives.

“The individuals who are responsible for this, if you’re not part and parcel to the murder of Khaseen Morris, now’s the time to get in touch with us and let us know who did this and why,” he told reporters. “If you were just coming here and thinking you were fighting, and then he got stabbed during that, you need to get out in front of that.”

Fitzpatrick continued: “After I put handcuffs on you, that ship has sailed.”

One of Morris’ friends, a 17-year-old, was also hurt during the attack and went to a hospital with a broken arm.

Morris’ sister, meanwhile, told Newsday that the ex-boyfriend had sent him “threatening messages,” but he wasn’t so concerned about it and didn’t plan on looking for a fight or running from one, either.

“No one knew he was going to bring a million people out there — and a knife,” Keyanna Morris said.

A candlelight vigil was held for Morris on Tuesday and another one is planned for Wednesday near a pizzeria where he was attacked. Those who plan on attending should wear tie-dye shirts and “look groovy as hell,” organizers posted on Facebook.