Madison police are adding extra patrols and searching for evidence in an attack that's unsettled the city and nearby University of Wisconsin campus."The cops were knocking on our door at 4 in the morning. So, kind of scary," said UW student Azza Bayoudh.Fellow students say police told them the 20-year-old woman was attacked around 3:20 a.m. Sunday, apparently by a stranger."It was just kind of terrifying because I was like, that kind of could've been me," Bayoudh said. "So that's what scared me. So we have our doors locked now and we hope they catch whoever it was." According to a neighbor, the young woman was walking on a sidewalk when she was forced into an area between two houses at Bedford and Wilson streets. Someone heard her crying for help and called police.A friend of the victim told WISN 12 News Monday the UW senior was strangled, beaten and sexually assaulted.She also suffered a broken jaw, but is said to be recovering after police Sunday said she was in critical condition.In the meantime, police are reaching out to neighbors with surveillance cameras or doorbell cameras, hoping one of them may have captured the suspect on video. Police say they’re also collecting DNA evidence."We're in the process of interviewing people, collecting evidence, taking photos and documenting the scene," said Madison police Assistant Chief Paige Valenta. "We are swabbing for biological evidence."The university put out an alert to students and parents. Many families just moved their students to campus over the weekend, with the first day of classes on Wednesday, Sept. 6. "I'm usually pretty cautious, especially at night, but definitely tend to hold my keys a little tighter, I usually have some other people walking with me at all times. I think that's the best thing. Travel in groups," said Abby Lokai, who lives just down the street from the scene of the attack. Police Monday did not give an update on the investigation. They have yet to release a description of the suspect.