DANVILLE — Parents of Los Cerros Middle School students were put on alert Friday after a man exposed himself to several students on a trail after school finished for the day.

At 2:35 p.m., Danville police received phone calls reporting a man who had flashed seven students at one time, Danville police Sgt. KC Wen said. Officers responded within minutes and searched the area for several hours.

The flasher was a white man in his mid 30s, a little over 6 feet tall, 165 pounds, with short brown hair. He wore a baseball cap, a white T-shirt and jogging shorts.

This is the second reported case of a man exposing himself to students at the school in the last three weeks, according to the Contra Costa Sheriff's Office.

A man matching the description of Friday's suspect and acting similarly was first reported at that time. The day of the previous occurrence was not available Saturday.

In an e-mail to parents, school Principal Phyllis Roach asked students to program the Danville Police Department's phone number into their cell phones in the event the flasher returns. Students can call police at 925-820-2144.