Photo taken on Nov. 20, 2018 shows the wreckage in the site where the wildfire engulfed in Paradise of Butte County, California, the United States. (Xinhua/Wu Xiaoling)

LOS ANGELES, Nov. 20 (Xinhua) -- The death toll from the massive wildfire in Northern California, dubbed the Camp Fire, has climbed to 81 with 870 still listed as missing, authorities said on Tuesday evening.

According to the update of the Butte County Sheriff, two human remains were located in structures in the town of Paradise on Tuesday, bringing the death toll from Monday's 79 to 81.

The number of the unaccounted for increased by 171 to 870, according to a release by the sheriff's office. However, officials found that the increase on Tuesday is due to the fact that detectives were able to work through a back log of voicemails.

The fire, which was first reported on Nov. 8 in Butte County, scorched 152,250 acres (616 square km), with 75 percent contained, and destroyed over 16,000 structures, including 12,637 houses, 483 commercial and 3,718 other buildings, according to the California Department of Forestry and Fire Protection (Cal Fire).

Cal Fire said that established containment lines continue to hold while firefighters work to strengthen and improve control lines around the remainder of the fire perimeter.

The agency also stressed that crews have accelerated suppression repair efforts in advance of expected rains. The National Weather Service issued a flash flood watch Wednesday afternoon to Friday morning for the fire area.

Local officials urged residents to be aware that the areas being lifted have very limited services.

"Prior to returning home, residents are encouraged to take steps to ensure they have food, water and fuel for their vehicles," said the Butte County Sheriff's Office.

The Camp Fire is now the deadliest and most destructive wildfire in California's history. It's also the deadliest wildfire in 100 years in the United States.