MONTECITO, Calif.  — The number of people missing since mudslides engulfed this wealthy coastal town surged to 48 Thursday as hundreds of rescue workers slogged through knee-deep ooze and used long poles to probe for bodies. The number of confirmed dead stood at 17.

The huge increase in those unaccounted for came as authorities investigated missing-persons reports, said Santa Barbara County spokeswoman Amber Anderson.

The number has fluctuated since the disaster struck in the early morning darkness Tuesday and was as low as 16 Wednesday evening. The new count raised fears that the disaster was far worse than authorities imagined.

Family members have been anxiously awaiting word on loved ones as the search goes on.

“It’s just waiting and not knowing, and the more I haven’t heard from them _ we have to find them,” said Kelly Weimer, whose elderly parents’ home was wrecked. The couple, Jim and Alice Mitchell, did not heed a voluntary evacuation warning and stayed home to celebrate Jim Mitchell’s 89th birthday.

As search dogs clambered on heaps of wood that used to be homes, mud-spattered rescue teams from all over California worked their way through the ruins of Montecito, an enclave of 9,000 people northwest of Los Angeles that is home to celebrities such as Oprah Winfrey.

It was left covered with thick muck, boulders, wrecked cars, splintered lumber and tree limbs in a scene Santa Barbara County Sheriff Bill Brown likened to a World War I battlefield.

After a better look at the damage, officials lowered the number of destroyed homes from 100 to 59 and raised the number of damaged ones from 300 to 446.

Overall, 28 people were injured. Twelve remained hospitalized, four in critical condition.

By Wednesday, some 500 searchers had covered about 75 per cent of the inundated area, authorities said. They had a long slog ahead, filled with hazards seen and unseen.

“A lot of the street signs are gone, the roads are impassable. It all has to be done on foot,” said Deputy Dan Page, chief of a Los Angeles County Sheriff’s Department rescue team.

Rescue crews worked up to 12 hours a day and risked stepping on nails or shattered glass, or being exposed to raw sewage, or dealing with leaking gas, Page said.

“We’ve gotten multiple reports of rescuers falling through manholes that were covered with mud, swimming pools that were covered up with mud,” said Anthony Buzzerio, a Los Angeles County fire battalion chief. “The mud is acting like a candy shell on ice cream. It’s crusty on top but soft underneath, so we’re having to be very careful.”

Crews marked where bodies were found, often far away from a home, and used that information to guess where other victims might have ended up as the surging mud carried or buried them.

People in Montecito had counted themselves lucky last month after the biggest wildfire in California history spared the town. But it was the fire that led to the mudslide, by burning away vegetation.

“We totally thought we were out of the woods,” said Jennifer Markham, whose home escaped damage in both disasters. “I was frozen yesterday morning thinking, ‘This is a million times worse than that fire ever was.”’

The mudslides were already occurring when Santa Barbara County officials first sent emergency alerts to cellphones in the area, the Los Angeles Times reported Thursday.

For days, the county had issued repeated warnings via social media, news media and emails about the potential for mudslides. But county emergency manager Jeff Gater said officials decided not to use the cellphone push alert system until 3:50 a.m. Tuesday out of concern it might not be taken seriously.

Only an estimated 10 to 15 per cent of residents fled when ordered, and much of the damage occurred where evacuations were voluntary.

It could take days or even longer before the work is finished.

“That’s always our mentality: ‘Hey, we’re going to find someone alive,”’ Page said. “You never really know. You never know exactly what the human body is capable of.”

In 2014, a mudslide in rural Oso in Washington state killed 43 people. The last body was found four months later.