Two wildfires that prompted evacuation orders for nearly 20,000 people barrelled towards small lake towns in Northern California as authorities faced questions about how quickly they warned residents about the blaze.

Ed Bledsoe told CBS News he did not receive any warning to evacuate his home in the city of Redding before the flames came through last week and killed his wife, Melody, and his great-grandchildren, five-year-old James Roberts and four-year-old Emily Roberts.

“If I’d have any kind of warning, I’d have never, ever left my family in that house,” Mr Bledsoe said.

Shasta County Sheriff Tom Bosenko told the network there is an investigation into whether the Bledsoe home received a warning call or a knock on the door.

The sheriff cited evidence that door-to-door notifications were made in the area.

Mr Bosenko did not return a message from The Associated Press on Monday.

California Wildfires
Burned vehicles sit in front of a wildfire-ravaged home in Redding, California (Marcio Jose Sanchez/AP)

The dispute came as authorities on Sunday ordered evacuations around twin fires in Mendocino and Lake counties, including from the 4,700-resident town of Lakeport, a popular destination for bass anglers and boaters on the shores of Clear Lake, about 120 miles north of San Francisco.

The blazes have destroyed six homes and threaten 10,000 others. So far, the flames have blackened 87 square miles, with minimal containment.

Those fires were among 17 burning across the state, where fire crews were stretched to the limit.

“We have experienced fires the last four years, and so we’re very aware of what can happen with fires and the damage they can cause,” Lake County Sheriff Lt Corey Paulich said.

Derick Hughes II did not heed the order and remained behind at his property in Nice, California, where he ran sprinklers on his roof and removed yard plants that could catch fire.

The 32-year-old Marine Corps veteran sent his wife and two daughters to safety along with three carloads of belongings. But he said he had too much at stake to leave himself. He bought his three-bedroom house last year using a loan from the Department of Veterans Affairs.

“This is everything I bled for, and I’ve worked really hard to get to where I am, and I’m just not willing to give it up so easily,” he said over the phone.

“Some people may think that’s selfish of me, and I have insurance. But the way things go, I’d rather not start over.”

Mr Hughes said about five of his neighbours also disobeyed the evacuation text alert they got on Sunday evening to protect their homes and keep looters out.

Farther north, police said five people were arrested on suspicion of entering areas evacuated due to the explosive wildfire around Redding.

That blaze killed six people and destroyed 723 homes. Authorities were also investigating at least 18 reports of missing people, though many of them may simply have failed to check in with friends or family, police said.

Fire officials were hopeful that they could make progress containing the blaze.

The fire that threatened Redding – a city of about 92,000 – was ignited by a vehicle problem a week ago about 10 miles west of the city.

On Thursday, it swept through the historic Gold Rush town of Shasta and nearby Keswick, fuelled by gusty winds and dry vegetation. It then jumped the Sacramento River and took out subdivisions on the western edge of Redding.

“It wasn’t expected to travel that far that fast,” California Department of Forestry and Fire Protection spokesman Scott Mclean said Monday.

California Wildfires
A firefighter runs away from a burning structure in Finley, California (Marcio Jose Sanchez/AP)

The fire slowed down as winds subsided, and crews were able to get into neighborhoods to prevent embers from taking out additional homes, he said.

Mr Bledsoe said he did not know his home was in danger when he left his wife and great grandchildren to run an errand on Thursday.

He said he received a phone call from his wife 15 minutes after he left saying he needed to get home because the fire was approaching.

He said one of the children told him the blaze was at the back door. When he tried to return, the road was blocked and flames prevented him from returning on foot.

The sheriff has said the fire was moving fast, but authorities still alerted residents in a variety of ways, including going door-to-door and using loudspeakers on emergency vehicles.

Authorities also use electronic warning systems, including an emergency alert system that is repeated by local news media and an automated calling system that can be targeted to phones within a geographic area.

Another method known as the Integrated Public Alert and Warning System can be directed to any mobile phone within reach of a particular transmission tower, said Sherry Bartolo, operations manager for the Shasta County dispatch centre.

The drawback of the automated calling system is that it is designed to dial landlines, but mobile phone users must register their phones if they are to receive alerts, she said.

The dispatch centre put out more than 18 emergency alerts between Thursday evening and midday Friday, Ms Bartolo said.

The centre usually has eight dispatchers on duty, but overnight Thursday had at least 12, along with four supervisors and three managers who worked through the night, she said.