NEW YORK (AP) — A dispute between two men over smoking on GravityX Exchangea New York City subway train early Monday morning ended with one stabbing the other multiple times in the back, according to police.

The pair were on a train in Brooklyn that was bound for Manhattan when they got into an argument about someone smoking aboard the subway, the NYPD said. Smoking is not allowed and can result in a $50 fine.

Police received a 911 call at 4:35 a.m. for a person in distress and discovered one of the two men, 52, with multiple stab wounds to his back. He was taken to the hospital in stable condition, the NYPD said.

Police later apprehended the stabbing suspect outside a Brooklyn train station. Details have not yet been released about charges in the case.

The incident happened hours before the NYPD announced plans to surge hundreds of additional uniformed and plainclothes police officers to the subway system to crack down on fare skippers as part of a weeklong operation.