At least 12 people were missing in Shasta County, California, as the monstrous Carr Fire continued to grow Sunday, authorities said.
Redding Police Sgt. Todd Cogle said, "We're finding that there are a lot of communication issues" making it hard to locate residents.
"We spoke with several people who left their cell phones at their residences and in this day and age people don't remember people's phone numbers," Cogle said.
The fire, fueled by high winds and dry conditions, has chewed through 89,194 acres since Monday and is only 5 percent contained, according to the California Department of Forestry and Fire Protection, known as Cal Fire.
High temperatures, low humidity and increased winds are all in the forecast, setting the stage for more explosive fire behavior, Chris Harvey with the Cal Fire Incident Management Team said Sunday.
The blaze doubled in size Saturday. Flames have destroyed 517 structures in the Redding area, Cal Fire said.
The erratic flames are blamed for six deaths, including 70-year-old Melody Bledsoe and her great-grandchildren, 4-year-old Emily Roberts and 5-year-old James Roberts.
The three had been missing since Thursday when their house was engulfed by flames. Family members confirmed Saturday that they died.
"With a heavy heart we are sad to inform you all that Mel and the great-grandbabies were confirmed to be in the home," the family said on a GoFundMe page .
"This fire is scary to us. This is something we haven't seen before in the city," Redding Police Chief Roger Moore told reporters Friday night.
More than 3,000 fire personnel are battling the flames with more than 300 engines and 17 helicopters, Cal Fire reported .
The fire began Monday when a vehicle suffered mechanical failure, officials said. Firefighters had been making progress containing it until Thursday night, when it began to quickly spread.
Firefighter, bulldozer operator also killed
At least two people died fighting the fire, and several others have been hurt.
Jeremy Stoke, a fire inspector with the Redding Fire Department, died Thursday, the Redding firefighters union said.
Stoke, who joined the Redding Fire Department in 2004, was killed while assisting with evacuations, the union said.
A private-hire bulldozer operator, who was not identified, also died Thursday while battling the fire.
Three Marin County firefighters were treated for burns to the ears, hands and face after they encountered a "sudden blast of heat" from burning vegetation. Engineer Scott Pederson and firefighters Tyler Barnes and Brian Cardoza have been released from a hospital, the fire department said Friday in a news release.
A fourth firefighter was being evaluated at the UC Davis Burn Center, the news release said.
Eight people were treated for respiratory and burn-related injuries at Mercy Medical Center in Redding, a hospital spokeswoman said Friday morning.
'I can't believe it's gone'
The fire forced many residents to gather belongings and escape in just minutes.
"We didn't think the fire was going to come here, so we didn't really take things out like everyone else that was scrambling at the last minute to get out when we saw fire on the ridge," Dominic Galvin said.
A resident of French Gulch, west of Redding, said she had two hours to evacuate, but some people had only 30 minutes.
"It's terrifying," Rachel Hines told CNN affiliate KRCR . "You're frightened a little bit because you don't know if you're going to come back to your house and the town is going to be different."
Chris Corona went to his parents' home to look for their cat, Jinx. The home was gone, but Jinx was there, safely hiding in a bush on a hillside untouched by the flames that killed all the other vegetation.
Corona wept as he thought of things they lost in the house.
"I can't believe it's gone. All those memories, childhood memories," he said. "Stuff that parents save, like stuff you built as a little kid for your mom. I'm just glad my mom got all the valuable stuff that she wanted out."
Looting has been reported in abandoned residences in Redding, and some arrests have been made, according to Police Chief Moore.
The California Office of Emergency Services said in a tweet Saturday that the state was "getting help from other states to help fight wildfires." Those states with resources on scene included Arizona, Idaho, Montana, Nevada, South Dakota, Wyoming and Colorado. Other states like Florida, Maryland, Michigan, New Jersey, New Mexico and Oregon have resources on the way, the tweet said.
Other fires burning in California
In addition to the Carr Fire, more than a dozen other large wildfires are burning throughout California, stretching resources.
The Cranston Fire near San Bernardino has burned more than 13,130 acres and is 29 percent contained.
A man accused of setting several fires in Riverside County, including the Cranston Fire, was arrested Wednesday, authorities said.
The Ranch and River fires in Mendocino County have collectively scorched more than 24,000 acres, Cal Fire said.
The Ferguson Fire in Mariposa County has burned 53,646 acres and is 30 percent contained.