A man walked onto the Patterson High School campus and exposed himself, then grabbed a female student at her locker before she was able to break free, according to the Stanislaus County Sheriff's Department.
The man fled before deputies arrived on the scene minutes later, according to Capt. Tim David.
The incident occurred Wednesday at 6:52 a.m.
The man was described as a cleanshaven Latino man in his 30s, 5 feet 6 inches tall, 180 pounds and wearing a blue sweat shirt and gray sweat bottoms.
He apparently walked up to the girl and accosted her before she began yelling and screaming and broke free. She then ran to the attendance office to report the incident.
Patterson Police Services provided extra patrol for the school Thursday morning and in the afternoon, and will continue to do so throughout the week, David said.
"We're very concerned about this and are putting resources to work in an attempt to identify and capture the suspect," he said. "We're working closely with the school."
Anyone with information or potential witnesses to the incident are asked to call Detective Michael Fisher at 892-5071.