A fire started shortly before 9 p.m. Friday in a classroom at Flory School in the mid-city area, the Ventura County Fire Department reported.
The first-floor elementary school classroom was fully engulfed in flames when firefighters arrived.
The fire was contained by 9:30 p.m., but another classroom also was damaged, fire officials said. More than 50 firefighters were on the scene late Friday.
The classroom is next to the offices of the Moorpark Unified School District at 30 Flory Ave.
Nearby is a storefront for the Ventura County Sheriff's Department.
The area is primarily residential.
Fire officials reported no injuries and said no other structures were immediately threatened.
A man who was not identified reported to deputies that he saw two people walking away from the campus area about the time the fire started.