BROOKLYN - Police are searching for a man who sexually assaulted a 31-year-old woman in Greenwood Heights early Thursday morning.

Authorities say the woman was walking on 6th Avenue between 23rd and 24th streets at around 7:15 a.m. when a man on a mountain bike groped her from behind and then fled.

Local residents were troubled by news of the daytime assault. Posters have been plastered throughout the neighborhood, urging people to be alert.

Police say the victim did not clearly see her attacker, but they say the man was last seen wearing a dark hooded shirt. Anyone with information about the incident is asked to call Crime Stoppers at 1-800-577-TIPS.