San Bernardino County Public Works crews raced to place sandbags across Potato Canyon Road.
But the barrage of wet weather means that things can change in a hurry. The sandbags were no match for a rush of debris flow that crossed the road.
This dangerous situation is exactly why there is a mandatory evacuation order in effect near burn scar areas from the El Dorado and Apple fires.
The impacted communities include Yucaipa's North Bench, Mountain Home Village, Oak Glen, Forest Falls and Lytle Creek.
MORE | OC residents rescued as mud flows through Silverado Canyon
This comes as Birch Creek gets closer and closer to overflowing its banks, right alongside a number of homes.
"The mud and debris comes down from the burn scars areas very quickly and it's treacherous, and firefighters cannot always get up into those areas, and you may be left on your own," said Tracey Martinez with the San Bernardino County Fire Department.
In Oak Glen, the primary concern is keeping the road from washing away.
"Oak glen, there's only a couple ways in and out, one on each side, and the roadways are already starting to wash over with debris and mud, and county public works and other agencies are trying to keep the road clear as best they can," Martinez said.
The swift-water rescue team is also on alert, just in case. Meanwhile, many people in Oak Glen have decided to stay put and ride out the storm.
"They've got all kinds of equipment stationed everywhere, and they've got lookouts everywhere, so we feel pretty confident it will be alright," said area resident Carlos Garcia.
Commuters should note that Highway 38 has been shut down between the ranger station and Big Bear due to widespread rockslides.
MORE | Rain soaks SoCal, flooding roads and knocking out power in some areas