New York City police have arrested a man and charged him with assault as a hate crime after a 24-year-old says he was punched in the face.

Police on Saturday were investigating whether it was part of a so-called "knockout" assault, in which the object is to knock out an unsuspecting person with one punch. The man says he overheard a group talking about it before he was hit.

Police say the victim told them he was walking in Brooklyn around 2:45 a.m. Friday when he was struck once. He was not seriously injured.

Amrit Marajh, 28, of Brooklyn, was arrested on charges of assault as a hate crime and aggravated harassment as a hate crime because the victim is Jewish. It wasn't clear if he had a lawyer.

Three others taken into custody were released.

Police are investigating similar recent incidents, including in New Jersey, Pennsylvania and Washington, D.C. At least two deaths have been linked to the attacks this year.

New York City police have deployed additional officers to city neighborhoods where at least seven attacks occurred in the past few weeks, including an assault on a 78-year-old woman.

Authorities and psychologists say the "knockout" assaults have been around for decades — or longer — and it's played mostly by impulsive teenage boys looking to impress their friends.