Police believe their suspect may have assaulted other women in the building as well.
The attack happened January 30th around 11:00 in the evening in the 700 block of Sligo avenue in Silver Spring, MD.
The woman told police the suspect entered the laundry room, locked the door and told her to turn around.
When she did not, he pulled out a knife and went towards her, that's when she started screaming for help.
The suspect is described as a black male between the ages of 16-18, with short black hair and a diamond earring in each ear.
He was last seen wearing a white t-shirt and white skinny pants.
Anyone with information is asked to call police at 1 866-411-tips.