Police are looking for a man who forced a woman into a Brooklyn alley at knifepoint and sexually assaulted her.

It happened around 6 a.m. Sunday on Louis Place in Bed-Stuy.

Authorities say the suspect approached a 24-year-old woman with a knife in his hand and followed her before grabbing her and forcing her into an alleyway between 19 Louis Place and 19A Louis Place. 

Police say the suspect pulled the woman's pants down and began to perform a sex act on her. The man also grabbed the woman's breasts and behind before taking her cellphone and running away.

Police released a sketch and video of the suspect, who appears to be running away after the alleged sex assault. He is described as being between 30 and 40 years old, 5 feet 6 inches tall and 190 pounds. Police say the suspect also has a mustache and was last seen wearing a brown shirt and blue shorts. 

Anyone with information is asked to call Crime Stoppers at 800-577-TIPS.