The fire began Saturday night at 6 p.m. northeast of Clearlake Oaks, near Pawnee and New Long Valley roads, Cal Fire said.
Thousands have been forced to leave their homes and seek safer ground as the fire continues its path of destruction.
PHOTOS: Pawnee Fire rages through Lake County
Lake County Sheriff Brian Martin said the fire is "unprecedented" because it is spreading at an alarming rate just a few days into summer.
Ten structures have burned and 600 more are at risk of burning as firefighters move quickly in the fire zone.
Captain Jordan Motta of Cal Fire told ABC7 News that crews are working overnight, employing bulldozers to build containment lines and hand crews working "in the terrain" to help get the fire under control. "It's our goal to get people back into their homes as fast as possible and as soon as it's safe."
RELATED: Firefighters battling Lake County blaze near Clearlake Oaks, 400 acres have burned
Motta added that the public should be ready for these dangers as fire season begins. "It's a reminder for the public to get ready for wildfire...it's what happens in the summer in California."
At least ten homes have been destroyed. Firefighters say the fire is moving fast and difficult to access.
"Fire was growing quite rapidly. Resources were aggressively working on that, primarily dozers and hand crews going direct on the fire, and the engines being utilized for structural defense," Cal Fire Division Chief Greg Bertelli said.
EVACUATION ORDERS AND RESOURCES
Mandatory evacuations have been ordered for the entire Spring Valley subdivision of Clearlake Oaks, Cal Fire said. The latest evacuation information can be found here.
Around 4 p.m. Sunday, officials expanded the mandatory evacuation area past Highway 20 to the north and east of Old Long Valley Road to Round Ball Road. The areas include Mule Skinner, Long Branch, Watertrough Road, Fintlock, Muzzleloader, No Guns, Antelope, Cougar, Marianne, Ramrod, and Moccasin.
Some residents only escaped with the clothing on their backs. Luckily a family ABC7 News talked to was able to get their cat out of their home as well.
Officials say to please remember your pets, personal belongings, computers, prescriptions, photos, paperwork, and phones if time allows. Please try to close all windows and doors as well when you evacuatee.
An evacuation center has been established at Lower Lake High School, located at 9430 Lake Street. The Red Cross is gearing up to handle up to 300 evacuees.
Sheriff Martin added that there is an alternative evacuation site at the Moose Lodge, which is located at the junction of Highway 53 and Highway 20. The lodge, which has a bar, restaurant, and can handle animals, is very popular with locals when fires break out.
Officials are encouraging anyone in the area to conserve water so that firefighters can use it to fight the fast-growing blaze.
There are multiple road closures in and around the Spring Valley subdivision. More than 20 engines have been dispatched to contain the blaze, as well as two helicopters and several air tankers. The fire is being driven by low relative humidity, strong winds, Cal Fire said.
Get the latest on the Pawnee Fire here.
#PawneeFire [update] off Pawnee Rd & New Long Valley Rd, northeast of Clear Lake Oaks (Lake County) is now 400 acres. Mandatory evacuations in effect: https://t.co/LoCjg6kBA8 pic.twitter.com/BCvQ8lItbJ— CAL FIRE (@CAL_FIRE) June 24, 2018