Rescue teams searching for victims of the mudslides that have devastated southern California made progress in extracting victims and identifying some missing people, even as the death toll rose to 17 people.

Crews were slogging through waist-deep mud to search damaged and buried homes and cars around Santa Barbara in the wake of the mudslides caused by heavy rain that have also injured at least 28 people. Officials warned that sustained flooding and downed power lines continued to make for an “unstable” situation.

“Today was an important and busy day for our search-and-rescue efforts,” Santa Barbara County Sheriff Bill Brown told reporters in the afternoon.

By Thursday, rescuers had whittled the roster of the missing down to eight people. Improving weather allowed them to rove over a larger area. Despite steady progress, Mr Brown warned of “a long and difficult journey for all of us” looming ahead.

“It was still very stunning to see the extent of the devastation, to see the breadth of the area that has been impacted so terribly by this,” he told reporters. “It is a massive operation we have underway”.

According to county officials, surging debris and water had obliterated some 65 single-family residences, damaged around 450 and threatened roughly 1,500 homes. Natural gas was shut off, thousands were without power and potable water was no longer flowing across the hard-hit town of Montecito.

Mandatory evacuation orders encompassed some 7,000 people, with officials having urged another 23,000 or so to leave hazardous areas voluntarily. The Santa Barbara County Sheriff’s office established an excluded zone where recovery efforts were most concentrated, asking people to stay away so rescuers could do their jobs.

While 50 people were rescued by helicopter due to blocked roads, at least four of the injured remain in critical condition.

At least eight of the deaths occurred in Montecito, a wealthy enclave northwest of Los Angeles where celebrities like Rob Lowe and Oprah Winfrey have homes.

Fourteen-year-old Lauren Cantin was luckily saved after rescuers spent several hours carefully sifting through rubble, slogging through mud and battling continued early morning rain.

“I thought I was dead there for a minute,” Lauren said to rescue workers as she was taken away on a stretcher to the hospital. She appeared to be in good condition despite being trapped for more than six hours in her home.

“To be able to have her come out safely and as unscathed as she was, it was pretty phenomenal,” Andy Rupp, a Montecito Fire Protection District firefighter, told NBC Los Angeles.

The mudslides were so powerful that foundations of homes were swept away in the first big storm of the season.

Adding to the complicated scene, boulders were also sliding down hills that had been ravaged during a number of recent wildfires which consumed the region last month – which included the largest such wildfire in California history.

California mudslides: in pictures Show all 9 1 /9 California mudslides: in pictures California mudslides: in pictures Emergency personnel carry a woman rescued from a collapsed house REUTERS California mudslides: in pictures Mudslides unleashed by a ferocious storm demolished homes in southern California AFP/Getty California mudslides: in pictures Emergency personnel rescue a 14-year-old girl from a house Santa Barbara County Fire Department/Handout via REUTERS California mudslides: in pictures A car piled up in debris EPA California mudslides: in pictures Emergency personnel carry a man covered in mud REUTERS California mudslides: in pictures Emergency personnel evacuate local residents and their dogs through flooded waters after a mudslide in Montecito REUTERS California mudslides: in pictures A damaged vehicle that was pushed by mudflow onto the US 101 Freeway EPA California mudslides: in pictures Los Angeles Fire Department Firefighters work admist flood waters EPA California mudslides: in pictures A semi-tractor trailer sits stuck in mud Santa Barbara County Fire Department via AP

The scorched land, stripped bare of any kind of vegetation which could have acted as a natural barrier to the boulders, did not absorb the torrential rains as it normally may have, causing flash floods in the Santa Ynez mountains.

In some places, the mud was nearly five feet deep.

Authorities had been bracing for the possibility of catastrophic flooding – it was the first time in 10 months the area has seen such heavy rain. Montecito in particular saw half an inch of rain in just five minutes in the early hours of Tuesday morning.

Despite an evacuation order for Santa Barbara, Ventura, and Los Angeles counties, emergency management authorities have said only 10 to 15 per cent of residents paid attention to it.

Power lines and even the steel poles holding them were swept away by the mudslides and a major thoroughfare – US Highway 101 – is expected to be closed for at least two more days since it is covered in a thick layer of mud.