At least 13 people were killed and 25 were injured in Santa Barbara County as Southern California's first winter storm swept through the region on Tuesday. The heavy rains triggered mudslides that swept several homes from their foundations.

Santa Barbara County Officials said at an afternoon news conference that about 7,000 people live in the mandatory evacuation zone, and about 23,000 people live in the voluntary evacuation zone. Officials could not confirm where in the county the deaths and injuries had occurred, nor how many people remained missing. However, at least six people were killed in the Montecito area, Santa Barbara County fire officials said earlier in the day.

The first confirmed death was Roy Rohter, a former real estate broker who founded St. Augustine Academy in Ventura. The Catholic school's headmaster, Michael Van Hecke, announced the death and said Rohter's wife was injured by the mudslide.

First responders were aware of approximately 300 people trapped in Romero Canyon, according to officials.

Residents were unaccounted for in neighborhoods hard to reach because of downed trees and power lines, Santa Barbara County Fire Department Capt. Dave Zaniboni told the Associated Press, which reported that there was a "backlog of scores of callers requesting help."

Between 3 a.m. and 6 a.m. Tuesday morning, dispatchers received more than 600 calls for help, officials said at the afternoon news conference. Fifty people had been hoisted to safety, and "dozens more" were rescued from the ground, officials said.

The Santa Barbara County Fire Department's Mike Eliason tweeted that the 300 block of Hot Springs Road was badly hit by mudslides. That area was not under mandatory evacuation orders, but voluntary ones, according to a map and press release circulated by the County of Santa Barbara.

In Burbank, the Deer Canyon basin overflowed, according to an update from city officials. The Upper Sunset Debris basin above Country Club Drive also overflowed Tuesday afternoon, Kerjon Lee with Los Angeles County Public Works said.

NBC L.A. captured footage of the resulting mudslides:

According to Lee, the Upper Sunset Debris Basin is under construction, so part of it had not been built yet. Lee called the resulting flows of water, mud and debris an "overflow," and not the result of a compromised structure.

Burbank Police Department public information officer Derek Green said, because of the damage from the areas burned in recent fires, the runoff was more than normal.

Debris runoff in Burbank also caused damage to a gas line and broke a fire hydrant. The storms also caused a three-quarter-inch gas leak to a line on Country Club Drive. As a result, residents on that road do not have utilities, according to an update from Burbank city officials.

Rescue crews used helicopters to lift people to safety because of blocked roads, and firefighters slogged through waist-high muck to pull a muddy 14-year-old girl out of the rubble of a home in Montecito. She was taken away on a stretcher.

Officials said they would declare a "rescue zone," and if unauthorized people go to that zone "willfully and knowingly," that they would be guilty of a misdemeanor.

Officials were unable to provide a number of structures damaged in Santa Barbara County, saying they were focusing their efforts on search and rescue.

As a result of the flash floods, the Montecito area is currently under a boil water notice. Residents are being advised to drink and cook with either bottled water or boiled tap water.

Around greater Los Angeles, crews worked to clear debris from roads, including a key stretch of U.S. 101 that was shut down along the border of Santa Barbara and Ventura counties. That's where thousands of residents evacuated Monday over fears of destructive mudslides in areas where the Thomas Fire, the state's largest-ever, raged last month.

Work crews also labored through the morning to clear mud from about a two-mile section of La Tuna Canyon Road west of the 210 freeway offramp at La Tuna. Though, by noon, rain resumed and much of the work was undone by new mudflows that blocked the road again.

At 11:30 a.m. a city emergency alert was sent to the area to evacuate due to the flash flooding hazard, and just before noon — less than half an hour after the alert — a wave of water, mud and boulders barreled down the La Tuna Canyon Wash.

KPCC's updated list of evacuations.

This post has been updated.