A woman told police that she was sexually assaulted by a man with a knife in Center City early Tuesday, and that he then fled with her panties, police said.

The woman, 24, flagged police down at 15th and Vine Streets around 3 a.m. and said an unknown man had pretended to help her find her roommate by apparently persuading her to walk from 15th and Locust Street to Vine.

The man then grabbed her from behind and demanded money, police said. The man took $5 and her debit card. He then sexually assaulted her, police said. He told her to close her eyes for five minutes or he would kill her. When she opened her eyes, she determined that the man had taken her underpants.    - Robert Moran