Los Angeles County prosecutors won't file criminal charges against 15 boys suspected of sexually assaulting two girls on and off a high school campus.

The district attorney's office announced Wednesday that there was insufficient evidence to file charges. Spokesman Greg Risling says one case was rejected in March and the others on May 8.

He declined to release details of the cases because they involved minors.

The 14- to 17-year-old boys attended Venice High School. They were arrested earlier this year amid allegations that they pressured or assaulted two teenage girls from the school, beginning in late 2013.

Police had said they believed some of the sex acts were forced and others were consensual but involved victims who were too young to legally give that consent.