Two University of Pennsylvania students were "terrorized" Friday by an intruder who held them captive in their apartment for four hours, police said.

To add to the terror, the women were rendered blind and mute during the ordeal after the thug placed duct tape over their eyes and fashioned duct-tape gags for their mouths, according to police.

The first victim, a 22-year-old woman, was leaving her off-campus apartment at 44th and Spruce streets when a man approached her in the hallway and forced her back inside at knifepoint, Special Victims Unit Lt. Thomas McDevitt said.

Once inside the apartment, the assailant produced a handgun, threatened the woman, then bound her.

About an hour later, the woman's 24-year-old roommate came home and also was bound by the man, who then sexually assaulted her, police said.

The assailant, who wore a black ski mask and black cotton gloves, did not sexually assault the first victim, according to police.

After four hours, the man left, taking with him a Dell laptop, two iPods, several cell phones, money and credit cards, police said.

The women were treated at Episcopal Hospital and released, McDevitt said.

It's unknown how the assailant entered the locked apartment building. Police speculate that either someone left the door ajar or that someone in the building let him in, McDevitt said.

Police believe that the same man may be responsible for a similar case on Oct. 22 on Clinton Street near 10th in Center City, in which a young woman and her boyfriend were accosted in the hallway of her apartment building by a knife-wielding man who tied them up, sexually assaulted the woman and stayed in the apartment for hours.

"It's very similar circumstances," McDevitt said. "They were both terrorized."

The suspect is described as a dark-complected black man, about 6-feet-1, in his mid-20s to early 30s, with short black hair, a goatee and light facial hair on the sides. *