(AP) — Police in New York, Washington and Jersey City are investigating whether recent random attacks on pedestrians are part of a violent game called “knockout,” where the object is to target unsuspecting pedestrians with the aim knocking them unconscious with one punch.

Authorities say the concept has been around for years and it’s played mostly by impulsive teenage boys looking to impress their friends. At least two deaths have been linked to the game this year and police have seen a recent spike in similar attacks.

New York City police have deployed additional officers where at least seven possible knockout-related attacks occurred in the past few weeks, including an assault on a 78-year-old woman. Police Commissioner Raymond Kelly said some are smacked, some are more seriously assaulted, and some harassed.