A voluntary evacuation order was issued in an Encino neighborhood where a heavy debris flow triggered by powerful rains damaged a residence on Monday, officials said.
Fire crews first responded to the 17900 block of Boris Drive around 4:55 p.m. after around 200 feet of mud pummeled into a home and guest house there, the L.A. Fire Department said in an alert.
"An entire hill came down" and the mud pushed through the guest residence before impacting the main home, according to Battalion Chief Andrew Wordin.
The mudflow was forceful enough to push the guest house off its foundation, and that structure was subsequently deemed uninhabitable. The main home, meanwhile, was determined to be unsafe, according to LAFD.
Three occupants, all adults, were able to escape safely with no injuries. They would be spending the night elsewhere, the agency said.
Homeowner Joyce Sachs said she wasn't home at the time, but her husband was.
"He said it was this a huge noise, a horrible, horrible sound like big a big thunderbolt or something," she told KTLA.
A grading expert evaluated the hillside to determine if other homes could be "in a slide zone," firefighters said.
No additional flows were expected Monday night, but with more storms on the way this week, "it is impossible to definitively predict what the hillside could potentially do," LAFD said in an alert.
The voluntary evacuation order covers 14 homes on Boris and Marston drives. Fire officials said residents were notified by police officers going door-to-door.
A geologist and grading expert would return to the scene at dawn to further assess the area ahead of incoming rain.
"My concerns are great at this point," Wordin said. "The forecasts are for a lot more rain, and given the amount of saturation that we've had already today, it's going to continue to get worse on this hill."
When asked if the voluntary evacuations could become mandatory, LAFD Capt. Branden Silverman replied that he "couldn't say right now."
"It's all going to be dependent on what the specialists say when they come out here and survey the hillside," he said. "But luckily, we aren't anticipating anything severe overnight, so we have a little bit of time to look and see what happens tomorrow."
Several miles southwest of that debris flow, crews were working to clear a separate one that was blocking a street in Hollywood Hills West.
Mud and a small tree that fell down a hillside were blocking the 2100 block of North Sunset Plaza Drive, LAFD said in a separate alert.
No structures were impacted and no injuries were reported.
Crews were working to chop up the tree and remove the debris. The Bureau of Street Services also responded to assist, firefighters said.
Earlier Monday, similar debris flows had forced the closure of Pacific Coast Highway in Malibu.
Officials subsequently issued evacuation orders for areas impacted by the Woolsey Fire.