New York City police are searching for a man who viciously assaulted an elderly woman on the subway this month.

Footage of the incident released on Friday shows the unidentified man continuously kicking the 78-year-old in the face as she sits by herself in the far corner of the train. Rather than helping the victim, several of the witnesses filmed the attack on their phones.

It remains unclear why the man targeted the older woman, but before getting off the subway car in the Bronx, he can be heard telling the witnesses to “WorldStar” the incident—an apparent reference to the website WorldStar Hip Hop, where violent videos have gone viral.

Police are asking for anyone with information to call 800-577-TIPS.