A sixth person was found dead on Sunday in the North California Carr fire that authorities say has grown to just under 90,000 acres.

The wildfire, which exploded Thursday, has taken six lives, including two firefighters, a woman and her two great-grandchildren, ages 4 and 5.

The sixth victim was not identified by officials during a news conference Sunday afternoon. Officials, however, said the victim — whose remains were found within the boundary of the Carr fire near Redding, about 230 miles north of San Francisco — didn't evacuate the area, despite warnings.

Seven missing persons reports remain outstanding, according to the Shasta County Sheriff's Office.

The National Weather Service alerted of a red flag warning in the vicinity of the Carr fire and remains in effect until Monday at 8 a.m. PT. The fire's spreading "is not driven by the wind, but rather the fire itself," the warning stated.

The highest threat remains near the city of Redding, the largest city in the region. The fire moved southwest of the town on Saturday, toward the small communities of Ono, Igo and Gas Point.

Keswick, a mountain town of just over 400 people, was almost completely wiped out, officials said.

The Carr fire remains the largest fire burning in the state, threatening more than 5,000 structures. The flames were just 5 percent contained as of Sunday.

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The latest tally showed at least 517 structures destroyed and another 135 damaged, California Department of Forestry and Fire Protection Anthony Romero said at the press conference.

"Right now, it's going everywhere," Romero said. "We still have a lot of open line. Any event could bring this back up again."

Anna Noland, one of nearly 38,000 people who were forced to evacuate the Redding area, learned through video footage that her house had burned in the fire. She planned to stay at a shelter while trying to find a place to live.

"I think I'm still in shock," Nolan told The Associated Press. "It's just unbelievable knowing you don't have a house to go back to."

'MY BABIES ARE DEAD': MOM, FAMILY MOURN FOR 2 KIDS, GREAT-GRANDMOTHER KILLED BY CARR FIRE IN NORTHERN CALIFORNIA

Wildfires around the state have forced roughly 50,000 people from their homes, said Lynne Tolmachoff, a Cal Fire spokeswoman.

About 12,000 firefighters were battling 17 significant fires Sunday in California, she said.

"We are well ahead of the fire activity we saw last year," she said. "This is just July, so we're not even into the worst part of fire season."

About 100 miles southwest of Redding, two blazes that prompted mandatory evacuations in Mendocino County destroyed four homes and threatened more than 4,500 buildings, officials said. They had blackened 39 square miles and were each 5 percent contained.

Authorities also issued evacuation orders in Napa County, famous for its wine, when a fire destroyed eight structures. The blaze had blackened 150 acres, but was 50 percent contained on Sunday.

Big fires continued to burn outside Yosemite National Park and in the San Jacinto Mountains east of Los Angeles near Palm Springs. Those blazes had burned nearly 100 square miles.

The Associated Press contributed to this report.