Police are looking for the person they said followed an 81-year-old man into his apartment building earlier this week and struck him in the head.

Investigators said it happened around 7:35 p.m. Wednesday at a building near East 10th St. and Foster Ave. in Kensington.

The man seen in the surveillance photo above then hit the 81-year-old in the head with an unknown object.

There is no word at this time about a motive, or the victim's condition.

Anyone with information on the case should contact the Crime Stoppers hotline at 1-800-577-8477, or text CRIMES and then enter TIP577, or visit www.nypdcrimestoppers.com