LOS ANGELES — In the days before the torrential rains came, authorities in the Southern California community of Montecito were worried that residents were suffering from “evacuation fatigue.”

After locals were forced to flee during last month’s record-setting wildfire, authorities wondered if they would go along with future directives to leave their homes.

Those concerns proved tragically on point as at least 15 people in the coastal enclave were killed early Tuesday in a massive flood of mud and debris, officials said, warning that the death toll could grow as about 24 remain missing and 28 others were injured. Many residents, they added, apparently failed to heed an earlier voluntary evacuation order — requiring more than 100 rescues and last-minute evacuations.

Now a community better known as a sunny vacation retreat and the home of celebrities like Oprah Winfrey and Rob Lowe is facing its second disaster in a little more than a month, after December's Thomas Fire.

And its recovery could be made more difficult because the neighborhood lies outside a designated flood zone. “Most of those homes, I would say, do not have flood insurance,"said Kelly Mahan Herrick, a local realtor and editor at large for The Montecito Journal.

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Photos: Rivers of mud sweep through wildfire burn areas in California

A map shows that the Santa Barbara County Fire Department made areas north of Highway 192 (also known as Valley Road) mandatory evacuation areas. That is in the upland sections of Montecito, closer to where the Thomas Fire cut a resolute path that would see it burn a total of more than 280,000 acres, the largest wildfire in California history.

Areas closer to the coast, and farther from last month’s fire zone, were under voluntary evacuation warnings, the map shows. It was in this area that Montecito Creek overflowed its banks at roughly 4 a.m. and began to flow into the neighborhood known as Montecito Oaks.

Olive Mill Road, close to the creek, turned into a river, delivering tons of water, mud and debris south toward Highway 101, according to local residents. By daybreak, the state’s main coastal freeway was rendered impassable, filled with mud, stray cars, boulders and hunks of ravaged homes.

The debris flow pushed into the garage and lobby of the signature Montecito Inn, the hotel with a red terra cotta roof that is a landmark on Coast Village Road. The street of small boutiques, brasseries and wine shops constitutes Montecito’s downtown. On summer days, it is crowded with tourists. On Tuesday, the block closest to the creek was filled with mud and downed trees.

With phone lines down and roads largely impassable, it was hard to know how much damage the businesses had sustained.

But the area will be largely cut off from the outside world for the time being, with the immediate closing of Highway 101, both in Montecito and to the south in Carpinteria, where the freeway also was inundated by flood waters.

Any losses will come on top of a slowdown local enterprises already suffered because of the Thomas Fire. The Four Seasons Biltmore, a luxurious resort, had just reopened Monday, after closing because of the fire. The historic hotel is located on Butterfly Beach, where the debris flow from Montecito Creek finally reached the sea.

After a single day with its doors open, the hotel evacuated guests Tuesday and closed down again, according to a Four Seasons employee, who declined to give her name. Some guests were moved to another Four Seasons property in Westlake Village, inland and well away from the floodwaters. There was no indication of when the Biltmore would reopen.

Just to the south, workers have been rebuilding a new iteration of another landmark hotel — The Miramar. Locals said it appeared that the Miramar property had not suffered any damage this week, though they expected construction to be slowed by the damage to the surrounding neighborhood and roads.

Herrick said homeowners in Montecito Oaks — where houses can sell for $1.2 million to $4 million and more — may find it particularly tough to rebuild this time.

“This is the most catastrophic thing we have been through,” the realtor and writer said. “People have lost loved ones or had them go missing. It’s heartbreaking. It’s just shattering.”