A “smoke-generating pyrotechnic device” used at the party caused the El Dorado fire in San Bernardino County, Cal Fire said in a press release.
The fire started at 10:23 a.m. on Saturday at El Dorado Ranch Park in Yucaipa and, according to the publication, spread from the park north to Yucaipa Ridge.
It has since grown to 7,050 acres as of early Monday morning, the Cal Fire Incident website shows.
Evacuations have been ordered for the parishes of Oak Glen, Yucaipa Ridge, Mountain Home Village and Forest Falls. According to Cal Fire, an evacuation warning is in place for the Yucaipa bank area and the Yucaipa Community Center is being used as a temporary evacuation facility.
More than 500 employees, as well as 60 engines and four helicopters, were used in the fire, according to the website.
The overnight weather is expected to remain hot and dry with a relative humidity of 20%, the San Bernardino National Forest said in its evening update on the fire. The winds also continue at three to five miles per hour with gusts of up to ten miles per hour resulting in “active fire behavior during the night”
No charges were announced in the flame.