Police say a woman was sexually assaulted early Sunday morning inside an apartment building in Bed-Stuy.
NYPD detectives say it happened around 12:30 a.m. on Bedford and Willoughby avenues.
Police say an unknown person slapped the woman on the buttocks before following her into the building.
Authorities say the person then sexually assaulted the victim before leaving the building.
The victim was taken to a hospital for treatment.
No arrests have been made as of Sunday night.