A father and his 18-year-old son were slashed by a man with a box cutter in Kensington early Sunday, cops and police sources said.

The violent encounter unfolded just before 1:15 a.m. at the intersection of 18th Avenue and East 2nd Street where the father and son got into an argument with three other men, according to cops and police sources said.

One of the men pulled a box cutter and slashed the 18-year-old in the face, neck and chest, cops said. The attacker also cut the 45-year-old man on the back of his neck, according to cops.

“I could them yelling and cursing,” Pasquale Trento, 42, told The Post. “The fight started from a business on 18 Avenue. I heard it was over money.”

Police were spotted putting a set of silver Rosary beads in an evidence bag at the scene.

Officers ran through the neighborhood, in and out of buildings and scaling fences, to track down the suspects as residents looked on, according to video from the scene.

Cops took away one man in cuffs, video shows.

The NYPD said they had one person in custody on pending charges.

The two others were not found.