Police spoke of their disgust today after about a dozen people looked on as a 15-year-old girl was beaten and gang-raped outside her high school homecoming dance.
The bystanders did nothing to help the girl, who was attacked by as many as seven men over a two-hour period outside Richmond High School, California, on Friday night.
"She was raped, beaten, robbed and dehumanised by several suspects who were obviously OK enough with it to behave that way in each other's presence," Lt Mark Gagan said.
"What makes it even more disturbing is the presence of others. People came by, saw what was happening and failed to report it."
The victim was in hospital today being treated for her injuries.
Manuel Ortega, 19, arrested at the scene, was being questioned today on suspicion of rape and robbery. He is not a pupil at the school.
Police said the girl left the dance and was walking to meet her father for a lift home when a classmate invited her to join a group drinking in the courtyard. The victim had drank a large amount of alcohol by the time the assault began, police said.
Officers received a tip about a possible assault on campus and found the girl semi-conscious near a picnic table.
Marin Trujillo, a spokesman for the West Contra Costa Unified School District, said there were four police officers and three school administrators monitoring the dance, but the assault happened away from the gym.