And that's just it, Steez. As stated in the link I posted above, it's illegal for a witnessed crime involving children to go unreported in CA. However...

"The Sherrice Iverson Child Victim Protection Act passed in 1999 makes it a misdemeanor to fail to report a crime against a child. However, the bill only applies to victims 14 or younger. The victim in the California gang-rape case was 15."

Yea, misdemeanor. So, unfortunately, there's no legal responsibility for the people who watched. Authorities have to wait it out and see if someone can be charged with possessing child pornography or something.