Five teenage males have been arrested, four of them juveniles who attend public schools in the Denver suburb of about 30,000 people, police said.
The girl who said she was assaulted is an Englewood High School freshman, school district spokeswoman Julie McGinley said. Police said they're looking for a sixth juvenile who also goes to Englewood schools.
The teenage girl reported being sexually assaulted January 25 at a house party involving alcohol and marijuana that was attended by 10-12 people, Englewood police said.
"If your student was at this party, knows someone who was there, or knows of students who have been affected by this event, we have counselors and other trusted adults should they need support or need to share their feelings," Superintendent Brian Ewert said in a letter sent to parents.
"We also ask that you be available to listen to your student and talk to him or her about his or her feelings regarding this event."
Police identified only one suspect, Daylon Benjamin Hill, 19, of Englewood. He was charged with five counts, including sexual assault and sex assault on a child. He is being held on $50,000 bond.
Police didn't identify the others because they are juveniles. Of those, two are 16 years old and two are 15 years old.
Officers started looking for the girl late Sunday night after taking a missing juvenile report, police said.
About the same time, other officers contacted the girl after she called relatives to say she had been sexually assaulted, police said.
A medical examination revealed "significant trauma consistent with sexual assault," according to a statement attached to Hill's arrest warrant