A wildfire burned 525 acres Thursday (July 16) and prompted authorities to evacuate two campgrounds in northern California’s Auburn State Recreation Area and a few homes in Placer County, fire officials said. 

The fire was 40% contained Thursday night, according to a California Department of Forestry and Fire Protection online report. 

Cal Fire spokesman Daniel Berlant said the fire started at about 2:30 p.m. near the middle fork of the American River east of Auburn, according to the Sacramento Bee

Authorities evacuated the Lake Clementine and Ruck-a-Chucky campgrounds and about two or three homes, Berlant said. 

He said 375 fire personnel fought the blaze in nearly triple-digit temperatures and dry conditions on steep terrain. 

Dozens of units involved included five air tankers and four helicopters. 

Berlant said the Mammoth Bar fire is a reminder to residents to be vigilant. A single spark can quickly grow into a large fire under hot and dry conditions like Thursday’s, he said. The cause of the fire remains under investigation.