BOULDER, Colo. -- Boulder police are searching for four men who gang-raped a woman in an alley early Friday morning.

The 20-year-old woman was walking home from a party when four men confronted her, she said. Two of the men held her down while two others sexually assaulted her, she said.

The woman ran home after the assault. Friends found her on her porch at 1:40 a.m., distraught and crying.

The friends called police. The victim was taken to St. Anthony's North Hospital, where she underwent a sexual assault examination.

The alleged assault occurred at about 12:45 a.m. along an alley that runs parallel to the north of Arapahoe Avenue. The exact location of the assault remains unclear, although the victim has indicated she believes it may have occurred in the 1800 block of the alley.

The victim told investigators that the four suspects had darker skin and may have been Hispanic. All had dark "slicked back" hair and appeared to be in their 20s. One of the men who assaulted her had a beard, she said.

The case remains under investigation.

Anyone with information about this crime is asked to contact Detective Colleen Wilcox at 303-441-3330. Those with information who wish to remain anonymous should contact Boulder County Crime Stoppers at 1-800-222-TIPS (8477) or 1-800-444-3776.

Tips can also be submitted via the Crime Stoppers Web site at www.crimeshurt.com. Those submitting tips through Crime Stoppers that lead to the arrest and filing of charges on a suspect(s) may be eligible for a cash reward of up to $1,000 from Boulder County Crime Stoppers.