Park Fire exploded overnight northeast of Chico, prompting evacuations in both Butte and Tehama counties Thursday. Cal Fire said the fire is at 45,549 acres and 3% contained as of 3 a.m. The fire started just before 3 p.m. Wednesday near Upper Park Road in Upper Bidwell Park, east of Chico and is burning to the north of the park. Chico isn't currently being threatened by the fire. The Park Fire is now the largest active fire burning in California, surpassing the Lake Fire in Santa Barbara County, which has burned 38,664 and is 90% contained. Evacuation orders and warnings are in place in both Butte and Tehama counties.