Rain comes down on areas ravaged by Woolsey Fire

MALIBU, Calif. (KABC) -- Fire-ravaged communities like Malibu and Oak Park braced for more potential disaster due to the first major Southern California rainstorm Wednesday night.

The Woolsey Fire charred nearly 100,000 acres in Los Angeles and Ventura Counties. Authorities said mud and debris flows are a very realistic threat during storms.

By 9:30 p.m., light rain started falling in Oak Park. Earlier in the evening, Josh Kaplan and his wife Kacy Grossman were getting ready for the storm's arrival by piling sandbags against the steep charred hillside behind their home in Agoura Hills.

Many were reminded of past tragedies like Montecito, where mudslides following the Thomas Fire left 21 people dead.

MORE: Southern California weather forecast

While many residents affected by the Woolsey Fire do what they can to protect property, some are prepared for the worst.

"If they tell us to evacuate, we're going to go because that was the right decision when the fire came," said Kaplan. "It was painful to leave but we would say the same thing to anyone, 'When you're told to evacuate, evacuate."

There was moderate rainfall in Malibu, where a mother and daughter said they were putting out hot spots earlier in the day and felt the rain was a welcome sight. Still the fear of mudslides remained.

"I still have my things packed, just in case if we had to get out 'cause up there, it's very bad, it's actually...we have, what, three houses left there," said Malibu resident Chaya Krause.

Firefighters said it takes a half inch of rain an hour to create huge debris flow, but with slick roads and loose gravel, they're urging people to slow down on highways and get sandbags to divert water to existing storm drains for the coming weeks, as there is more rain in the forecast.

PHOTOS: Southern California wildfires