Fire officials say a 3- to 5-acre brush fire is burning at the northern end of Griffith Park in Los Angeles.
Celebrities including Gwen Stefani and Gavin Rossdale frequent the park and live nearby.
Los Angeles Fire Department spokesman Ron Myers says 75 firefighters are either at the scene or en route to the blaze, which was called in at 12:42 p.m.
Myers says the fire is burning in an area of heavy brush and four helicopters are dropping water on it.
Griffith Park is one of the largest urban parks in the U.S. and is home to the Los Angeles Zoo and the Greek Theatre.
Myers says there are no reports of injuries or threatened structures. The fire is moving slightly toward the south.
Myers says the firefighters are still sizing up the situation.