RICHMOND, Calif. -- Police released a 911 call in which a shaken young woman tells a dispatcher about a drunken, naked girl on a high school campus whom officers later said was gang-raped by as many as 10 people.

The one-minute call is apparently the first report police received about the Oct. 24 attack during a homecoming dance at Richmond High School.

Police said as many as 20 people watched the attack in a dimly lit courtyard without calling police.

Margarita Vargas, a former Richmond high student who identified herself to the dispatcher only as "Maggie," said she hadn't actually seen the girl but learned about her from a family member who heard people bragging about the incident.

"We didn't want to go back there because we were scared," Vargas told the dispatcher. "Nobody wants to call the cops, so we decided to call the cops."

Police said the victim left the homecoming dance and was walking to meet her father for a ride home when a classmate invited her to join a group drinking in the school courtyard. Officers later found her semiconscious and partially naked near a picnic table.

Six suspects have been charged with rape.