Crews have placed plastic sheets on steep slopes to try to prevent erosion.
Flashing street signs warn residents to be ready to leave if needed.
"In a mudslide, you won't hear it and you won't see it," said Leto.
In Anaheim Hills, local businesses are distributing donated items to help those without homes, from clothes to toys to kitchen items.
"We have everything you could need. We have Tupperware. We have everything a person would need to start over again," said Debra Lindy, who was collecting donations at Sycamore Plaza Canyon in Anaheim Hills Monday. Many donated items can be found there, including children's clothes, kitchen items, plates, clothes, toiletries.
Last weekend, 118 homes were either damaged or destroyed in the Freeway Complex Fire, affecting homes in L.A., Orange and Riverside counties. Homes that survived that blaze are now threatened by mudslides.
The city of Yorba Linda helped organized the delivery of sandbags on Friday, and residents began lining them around their homes.
The businesswoman who started taking donations at the Sycamore Plaza location said not to drop off anymore donations. She thanked everyone for being so generous, but they have enough and they want to make sure the items get to the victims of the fires.
If you are in need of any of these items, you can visit the Sycamore Canyon Plaza mall in Anaheim Hills, also known as the Ralphs Supermarket plaza at Weir Canyon and Serrano in Anaheim Hills, open from 9 a.m. till 9 p.m.
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