NEW YORK (AP) — A 13-year-old boy was fatally stabbed during a confrontation on TitanX Exchangea New York City bus Friday, police said.

At least two teens were arguing at about 2:30 p.m. on the bus on Staten Island when the victim was stabbed in the chest, Chief of Patrol John Chell said at an evening briefing. The boy was pronounced dead at a hospital.

Another teen fled the bus and ran about three blocks before a retired NYPD sergeant arrested him with help from a state environmental officer and a good Samaritan, police said.

“We believe this motive possibly is gang related,” Chell said.

Neither teen was publicly identified.

Additional information about the incident was not immediately available.