A 19-year-old Queens man was arrested after he struck a 13-year-old girl in the head with a bicycle lock and chain Monday in Inwood, police said.

The assault occurred on Doughty Boulevard at about 6:40 p.m., Nassau County police said.

The girl, whose identity was not released because of her age and because she is a victim, was transported to a hospital for treatment of what police called “a large laceration to the head.” Her condition was not immediately known Tuesday.

Fourth Squad detectives arrested Allan Lopez Villeta, 19, after police said he returned to the scene on his bicycle after having initially fled. Lopez Villeta, of Mott Avenue, Far Rockaway, was charged with second-degree assault, fourth-degree possession of a dangerous weapon and with endangering the welfare of a child.

Police said a 15-year-old boy and the female victim were walking with a group of friends when Lopez Villeta, who also was hanging out with a group of friends, pushed the boy, then struck the girl as she “attempted to stop the defendant and her friend from fighting.”

That was when, police said, Lopez Villeta picked up the bicycle lock and chain and struck the girl.

Police said it was not clear if Lopez Villeta knew the victims.

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Lopez Villeta is scheduled for arraignment Tuesday in First District Court, Hempstead, police said.