LOS ANGELES » Los Angeles police say a 10th teenager has been arrested in connection with a series of sexual assaults against two Venice High School students.

Officer Jack Richter says the teen turned himself in to authorities Friday afternoon.

Eight other teens were arrested at the school Friday morning and a ninth surrendered later.

Police have said a total of 14 youths are under investigation for a series of sexual incidents both on and off campus dating back to the end of 2013.

"This is a painful moment for Venice High School and this district," Los Angeles Unified interim Superintendent Ramon Cortines said, adding that crisis counselors would be stationed at the school to assist students.

Smith said some of the incidents were forced sex acts, while others were consensual "but with victims too young to give consent." Most of the attacks are believed to have taken place recently, and Smith said police have physical evidence, though he declined say what. Detectives believe the students knew most of their alleged assailants.

"Incidents like this are a terrible tragedy," Smith said. If there are any additional victims, he said, "We’d ask them to come forward."

The former leader of the school’s PTSA said she was unaware of any issues at the school preceding the arrests.

"I’ve been part of the school for some time, I haven’t heard anything whispered even," said Linda Patterson Salib, who was president of Venice High School’s PTSA until February. "So this comes as quite a surprise. It’s not like, ‘Oh we knew there was a problem.’"