Farb Middle School in the Tierrasanta area has been locked down due to police activity.
The lockdown was ordered at about 3:50 p.m. at the campus, located at 4900 La Cuenta Drive, according to San Diego police.
School police said someone heard a single gunshot behind the school, but the SDPD said they did not find any suspicious activity in the neighborhood.
Officials lifted the lockdown about 10 minutes later.