Two separate 911 calls placed by female University of Washington students during the same home invasion thwarted a convicted rapist who had held their six female roommates hostage at knife-point.

The dramatic 911 recordings were released Tuesday by King County authorities, more than one week after the March 5 incident in which prosecutors allege that Robert Hitt broke into the Seattle-area home of eight University of Washington coeds.

As Hitt allegedly broke into the home around 3:30 a.m. and grabbed six of the roommates, Kings County dispatchers responded to a 911 call from a woman in a downstairs bedroom.

The caller told the dispatch operator that an intruder was in the house and she could hear her roommates scream.  "It sounds like she's alright, but it sounds like he's harassing her so I'm scared for her," the caller said.

Just moments later another call came into the King County dispatch line, this one from a woman in one of the home's upstairs bedrooms, who told the dispatcher she was hiding in a back corner but could still hear the intruder making threats.

"I'll stab you," she reported the intruder as saying.

The same woman also reported hearing the sound of duct tape ripping from the roll as Hitt taped her roommates just a few feet away.

"He's taping her…he's taping her somewhere," she said.  "I'm worried he's going to come find me."

"They're screaming, should I go?" she asks on the call.

The 911 dispatcher told the woman to remain in the room as police surrounded the house.  They arrested the suspect without incident.

None of the women were injured in the robbery.

Hitt was charged by King County police with nine felonies, including kidnapping, robbery and sexual motivation for allegedly forcing one of the woman to remove her clothes.

He could face up to a life sentence if convicted, ABC affiliate KOMO reports.