The most recent attack came on Friday. Police say a woman was attacked as she tried to enter her apartment about 2 a.m. The victim's roommate and boyfriend scared off the attacker.
"We heard screaming. he just, like, realized what was going on and just, like, ran out, and I stayed in my room and called 911," said the victim's roommate.
In the other cases a woman was sexual assaulted and another woman was attacked inside a university building.
Police are trying to determine if any of the attacks are related.