DENVER -- Police in Boulder are investigating a reported sexual assault after a woman was found on the University Hill area and said she had been assaulted.

The 21-year-old woman was found by passers-by at about 9:30 p.m. Tuesday in the area of 12th and College streets, said police spokeswoman Sarah Huntley.

The passers-by helped the woman home and her roommates took her to the hospital, Huntley said.

At the hospital, the woman told police she had been assaulted sometime earlier in the evening in the area of Grandview Avenue and Broadway street, she said.

Investigators said they have been unable to find the exact spot where the assault happened. Huntley said investigators are still working with the victim to build leads.

Police said they have no suspects so far. They do not believe the case is related to other sexual assaults reported in Boulder, Huntley said.

Anyone with information in this case is asked to call Boulder police at 303-441-3330 or Crime Stoppers 1-800-222-TIPS (8477).