Police Lift Lockdown At Mt. Diablo High School

CONCORD, CA — Mount Diablo High School was briefly placed on lockdown Monday while police investigated a concern reported by staff.

The lockdown was announced shortly before 10:30 a.m. Monday and was for precautionary measures only, the Concord Police Department said on Twitter.

"Officers are onscene investigating a concern reported by staff," police said. "There has not been a shooting at the school and no one was seen with a gun."

In a follow-up tweet at 10:51 a.m., police said the lockdown of the campus at 2450 Grant St. in Concord was lifted.