Fire investigators Tuesday tried to pinpoint what started a five-acre Cotati area blaze that destroyed three homes and displaced three families.

Investigators are considering a car backfire, fallen power lines and other possibilities, said Cal Fire Division Chief Eric Hoffmann.

The fire started on the south side of Highway 116 near Stony Point Road. It quickly jumped the highway, caught the dry grass on the north side and spread to the nearby homes. One of the three homes was uninhabited, and a total of four people were displaced, Hoffman said.

A Rancho Adobe fire engine from downtown Cotati arrived within six minutes of the 4:06 p.m. call from the dispatch center.

Battalion Chief Herb Wandel immediately called for a second alarm, wanting more help and water because of threatened property and the potential for the fire to burn across the dry fields.

Firefighters quickly faced a challenge as downed power lines blocked the best route to the fire.

They instead traveled through neighboring properties, cutting fences as they went.

About 2,100 PG&E customers lost power at around 5:15 p.m., said Brittany McKannay, spokeswoman at PG&E.

"We had crews out in the area just ready to help in any way possible," McKannay said. "We de-energized some of the lines … so they would be safe to work around."

Embers carried by wind also caused a few significant spot fires up to half a mile away.

"It was a little bit tense … in the first few minutes," said Wandel.

The residents have gotten help with temporary shelter by friends and family and in one case, a landlord, said fire officials. Damage to the homes was estimated at $700,000. A total of five acres burned.

Power was restored to most of the affected homes by 7:30 p.m. Monday, and the last 300 customers had power restored by 6:50 a.m. Tuesday.

The Highway 116 fire was at least the third of the day in the region and the second within minutes in Sonoma County.

At about 3:50 p.m. a vegetation fire broke out on the east side of the county, near Schellville, bringing firefighters from Schell-Vista and Sonoma.

Wandel's call for a second alarm in Cotati scrambled firefighters from several Sonoma County agencies and Cal Fire to join the effort.

Some firefighting airplanes stationed in Sonoma County had already been sent to Mendocino County Monday afternoon for what became a 200-acre fire south of Fort Bragg.

Air tankers for Cotati came from Grass Valley and a helicopter came from Los Gatos, said Cal Fire's Hoffmann.

"We still have a long run of warm weather coming in," said Wandel. "The wildland season is still here."

Staff Writer Cathy Bussewitz contributed to this report.

You can reach Staff Writer Randi Rossmann at 521-5412 or