Update, 10 p.m.: Lake County Sheriff Brian Martin announced the arrest of a Clearlake man -- Damin Pashilk, 40 -- on charges he set the Clayton Fire on Saturday evening. Details: Arson Arrest Announced in Devastating Lake County Fire.

Update, 1:30 p.m. Monday: The Clayton Fire in Lake County has engulfed over 4,000 acres and is 5 percent contained. More than 175 structures have been destroyed and another 1,500 are threatened. Over 1,600 firefighters have been deployed to the area.

KQED's Sukey Lewis checked in with her impressions of the badly damaged section of the town of Lower Lake. "The air is really heavy with smoke. There's ash drifting down. There's burned out cars and burned out lots that are very reminiscent of last year's Valley Fire. The hills behind the shops are bright red with flame retardant. There are fire crews pulling through, they're assessing the damage and trying to contain the fire," Lewis said.

AT&T spokesman Leland Kim says that some customers in Lake County may be experiencing issues with their wireline services.

"Our network technicians are investigating the issue and will work to resolve it as soon as fire officials determine the location is safe to perform repairs," Kim said. "We apologize for this inconvenience."

The Federal Emergency Management Agency has also authorized the use of federal funds to assist the state to combat the Clayton Fire. The Fire Management Assistance Grant Program (FMAG) will provide federal funding for up to 75 percent of eligible firefighting costs.

Eligible costs covered by FMAGs can include expenses for field camps, equipment use, repair and replacement, tools, materials, supplies and mobilization, and demobilization activities.

Updated, 11:30 a.m. Monday

Cal Fire reported Monday morning that the Clayton Fire destroyed at least 175 structures in the town of Lower Lake, in Lake County 80 miles north of San Francisco. That toll is expected to rise as the damage assessment continues.

The agency still reports the blaze at 3,000 acres and 5 percent contained.

The main challenges for firefighters on Monday -- stopping the fire from spreading into the town of Clearlake, where thousands of people have been evacuated on the town's east side, and building containment lines in 100-degree temperatures.

Weather conditions late Sunday and early Monday, which featured gusty winds from the southwest, helped push the fire to the northeast and toward the burn scar from last year's Rocky Fire

More than 1,000 firefighters have been deployed in and near Lower Lake and Clearlake. Bay Area departments that have sent units include San Francisco, Oakland, Albany, Piedmont, Fremont, Crockett, Moraga-Orinda, San Ramon Valley and Contra Costa and Alameda counties.

Original post: For the fourth time in little more than a year, a wildfire is raging out of control in Lake County, with a blaze destroying numerous homes in Lower Lake on Sunday along with much of the town's business district.

The Clayton Fire started Saturday evening. The blaze intensified at midday Sunday as the temperature hit 100 and gusty winds sprang up. Soon, flames were racing to the outskirts of Lower Lake and Clearlake, forcing residents out of their homes.

Cal Fire estimated at 8 p.m. Sunday the blaze has burned 3,000 acres and is only 5 percent contained.

Lake County Sheriff Brian Martin said during a Sunday evening news conference that the fire had devastated Lower Lake, a town of 1,300 near the southeast end of Clear Lake. Martin added there was no formal count yet of the number of structures destroyed.

San Francisco Chronicle reporter Evan Sernoffsky supplied a running account Sunday afternoon of the fire's progress through the Lower Lake. Just after 4 p.m. Sunday, he reported having witnessed scores of homes destroyed along and near Riverview Drive and Quarterhorse Lane:

Firefighters' radio traffic monitored on WildlandFire.com indicated that the conflagration had reached the Main Street business district in Lower Lake, with multiple buildings reported on fire. Commanders ordered helicopter water drops to try to protect surviving structures.

Here's Sernoffsky's video of the Main Street scene:

Radio traffic suggested that an effort to contain the fire along Cache Creek and Dam Road, on the north end of Lower Lake, had failed. The fire was reportedly continuing to expand toward the southeast corner of Clearlake.

Those reports came after Sheriff Martin, in his role as the county's emergency services director, declared a local public emergency "due to the disastrous conditions."

Saturday evening, the sheriff's office ordered areas south and east of Lower Lake to evacuate. As the blaze gathered momentum midday Sunday, mandatory evacuation orders were abruptly expanded to include all of Lower Lake and the Avenues area of Clearlake, a sprawling tract east of Highway 53.

The total number of residents under evacuation orders wasn't clear, but it includes all of Lower Lake's 1,300 people and perhaps one-third of the 15,000 inhabitants of neighboring Clearlake.

During Sunday night's press conference, Sheriff Martin pleaded for residents to heed the orders to leave.

"There have been several occasions today where we've had to go in and rescue people who refused to evacuate and later required assistance from first responders," Martin said. "I've said it before and I'll say it again -- that takes away from their primary mission, it unnecessarily puts our first responders at risk when people ignore evacuation orders, and I implore you to please comply with those evacuation orders."

Evacuation centers were opened at the Highlands Senior Center in Clearlake, the Twin Pine Casino in Middletown, Kelseyville High School and the Seventh Day Adventist Church in Lakeport.

Among the evacuees were patients at St. Helena Hospital Clear Lake, who were moved to a facility in Lakeport.

The Chronicle's Sernoffsky said via Twitter he witnessed numerous homes burning in the Bonham Road and Mustang Court area on the east side of Lower Lake.

Among those who readily complied with evacuation orders was Susan Smith, a resident of Mustang Court. Interviewed at the Highlands Senior Center, she said she left her home Saturday evening shortly after the fire started just to be safe. After a night at a motel, she was heading back home when mandatory evacuation orders were issued.

She had two big worries on Sunday. First, the whereabouts of her disabled 35-year-old son, whom she said has medical needs.

"I had him sent to St. Helena Hospital," she said. But then the facility was evacuated.

"Now I'm really worried about where my son is," Smith said. "I have no way to contact the hospital, because I'm sure they're very busy. It's going to take a while to track him down."

Smith's other concern: the fate of her home and her neighborhood of 17 years.

"There are so many people here I know," she said of the crowd at the evacuation center.

"You lose your home, it's devastating, you lose something of yourself," Smith said, crying. "It's your roots. And right now my roots are not there. I feel displaced."

About 1,000 firefighters were on the scene Sunday evening, with units rushing to the scene from all over Northern California. Among the Bay Area departments responding to calls for help were the San Francisco Fire Department, which dispatched five engines and a strike team, and the Contra Costa County Fire Department, which sent two engines.

Clearlake and Lower Lake adjoin each other at the southeast end of Clear Lake and were threatened in August 2015 by the Rocky and Jerusalem fires. Those two blazes burned scores of homes but were largely overshadowed by September's Valley Fire, which destroyed 1,200 homes in Middletown and nearby communities further south in Lake County.

Sernoffsky and Chron colleague Vivian Ho talked to residents in the outskirts of Lower Lake as the fire approached early Sunday afternoon:

Rick Davis, 40, stood on a rooftop in the Morgan Valley area with his garden hose as flames surrounded him on three sides and huge walls of smoke wafted up.

“I don’t know what to do,” he said. “I’m just trying to keep the roof wet so if an ember hits, it won’t all go up.”

Davis had gone to lunch in Lower Lake when the fire was calm and the threat of his home burning was low. When he heard the flames had started up again, he rushed home to try to do what he could.

“I’m just scared,” he said. “The wind can just change.”

A short distance east of Davis’ home, Garrett Reed, 43, watched the flames grimly.

“If I see embers and ash rain down, I will turn the sprinklers on the roof and get out,” he said. “But this is my grandfather’s house and I’m not going to lose it.”

The Clayton Fire is eating up the dry brush and trees left behind by major fires that recently tore through Lake County. The Rocky and Jerusalem fires scorched the region northeast of Davis’ and Reed’s homes, while the Valley Fire claimed the area to the southwest.

“I grew up here,” Reed said. “These are all my friends’ houses that are burning, All you can do is pray for the best.”

This post contains reporting from Jason Morash of Mendocino County community radio station KZYX.