Police: Gang rape outside California school dance lasted over two hours

As of late Monday, two suspects had been arrested in the case and a third was being questioned.

"There is one individual in custody who has made some spontaneous statements that have led me to believe that he is culpable for what happened," Richmond police Lt. Johan Simon said.

Nineteen-year-old Manuel Ortega, described as a former student at the school, was arrested soon after he fled the scene and will face charges of rape, robbery and kidnapping, police said.

A 15-year-old was later arrested and charged with one count of felony sexual assault. A third teenager was being interviewed, according to Lt. Mark Gagan of the police department in Richmond, California.

"Based on witness statements and suspect statements, and also physical evidence, we know that she was raped by at least four suspects committing multiple sex acts," Gagan said.

Investigators said as many as 15 people, all males, stood around watching the assault, but did not call police or help the victim, a 15-year-old student at Richmond High School in suburban San Francisco.

"As people announced over time that this was going on, more people came to see, and some actually participated," Gagan said.

Authorities had interviewed the victim, and the search for other attackers and bystanders who watched and did not report the rape was in "full-court press," according to Gagan.