Flash floods are sweeping through areas burned by California wildfires

A firefighter watches as a helicopter drops water to combat the Holy Fire in Lake Elsinore, California in August.

(CNN)Flash floods carrying piles of debris are sweeping through rain-drenched parts of California that were affected by recent wildfires.

In Southern California, evacuation orders and flash flood warning are in effect in some communities affected by the Holy Fire, which burned more than 22,000 acres earlier this year.
Cal Fire of Riverside County issued mandatory evacuation orders as thunderstorms have increased the risk of mudslides and debris flows in some areas. The department urged people to keep checking its site for current warnings and orders as boundaries keep shifting.
The department released time-lapse footage showing floodwater rushing through burn scars in Leach Canyon, Coldwater Canyon and McVicker Canyon Thursday morning.
    "We cannot stress enough the importance of heeding all warnings and road closures during this rain event!" the department said on Twitter.
    In Orange County, a mandatory evacuation order is in effect for Trabuco Creek area of Trabuco Canyon, which was briefly deluged by rushing waters of sludge debris. The Rose Canyon and Mystic Oaks/El Cariso North areas are currently under a voluntary evacuation warning.
    In Northern California, a flash-flood warning remains in effect for areas scorched by the Camp Fire, the state's deadliest and most destructive wildfire. One to two inches of rain fell in just an hour Thursday afternoon, mostly between Chico and Paradise, the National Weather Service said.
    The rainfall has flooded roads, stranded motorists and closed Highway 99 and Highway 70. Excessive rainfall over the burn scar caused debris flows consisting of rock, mud, vegetation and other loose materials, the weather agency said.
      "This is a dangerous situation. Persons within the Camp Fire Burn Area need to be alert for the potential of mud and debris flows. These flows could impact area roadways, hill sides, and local streams and creeks," the weather service said. "If you observe movement of soils, debris, or large amounts of water, you should move to higher ground immediately. Do not drive through water flowing across roadways."
      A flash-flood watch was also in effect through Thursday morning for communities scorched by the Mendocino Complex and Carr fires, which each burned hundreds of thousands of acres.