Child prostitution is thriving in San Bernardino County.

Hundreds of teens selling sex make connections using Internet sites like Craigslist.com, simply standing along a two-mile stretch of Holt Boulevard in Ontario or hooking up at local truck stops, investigators said.

A prosecutor and three Ontario officers described the underground teen sex industry in the report "Lost Innocence" on Friday at the Juvenile Law Institute Delinquency Law Program at UC Riverside Extension.

San Bernardino County prosecutor Tamara Ross said 91 prostitution cases have been filed in Juvenile Court in the past four years.

But Ontario police say they made 300 teen prostitution arrests in just one year. They are often treated as victims, so they aren't prosecuted.