The affected area in Topanga State Park in the Santa Monica Mountains is approximately 20 miles west of downtown Los Angeles.
About 750 acres have burned and there is 0% containment, the department said.
According to the tweet, two zones marked 4 and 6 on the department’s tactical map have been assigned to evacuate.
Zone 4 includes everything east of Topanga Canyon between the Community House and View Ridge. Zone 6 is each north of Entrada, south of Oakwood, and east of Henry Ridge, the department said.
It is unclear how many homes or residents are currently affected by the mandatory evacuation order.
The cause of the fire is being investigated and no injuries were reported by the end of Saturday, according to the department.
This is a developing story and will be updated as more information becomes available.