BROOKLYN - Police say a woman riding the F train allegedly awoke to a man rubbing against her in a sexual manner early Thursday morning.

They say the 27-year-old woman pushed the man away and he ran off the train at the Neptune Avenue stop.

Police are calling the alleged incident a criminal sex act.

They say the suspect is about 20 years old and stands about 5 feet 11 inches tall. He was wearing a dark hooded sweatshirt and blue jeans at the time of the incident.