A suspect was in custody and police were looking for others Monday in the rape outside a Richmond High School homecoming dance Friday, the San Francisco Chronicle reported Monday.
"What's shocking about it is there were so many people willing to involve themselves in such a serious crime," Richmond Police Lt. Mark Gagan said.
The victim, a student at Richmond High, left the dance about 9:30 p.m. PDT and was walking alone, expecting her father to pick her up, police said. A schoolmate invited her to join others who were hanging out and drinking on campus, Gagan said -- noting the girl drank a large amount of alcohol before she was raped by others in the group.
Gagan said police responded at around midnight to a tip about the assault and found the victim semi-conscious.
Police said they arrested Manuel Ortega, 19, on suspicion of rape, robbery and kidnapping. Ortega is not a student at the school.