NEW YORK - Police are investigating the death Wednesday of a man on the Upper East Side as a homicide.

Investigators say officers assigned to the 19th precinct were called to the victim's apartment building at 120 East 83rd Street just before 7:30 a.m.

When they arrived, they found the 64-year-old man laying face down in the living room unconscious and unresponsive with a gash to the head.

He was pronounced dead at the scene.

Police say it appears the man was struck by someone else, saying there was nothing found in the vicinity of the victim that would have caused the injury.

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.