Three fast-spreading California wildfires sent people fleeing, with one trapping campers at a reservoir in the Sierra National Forest, as a brutal heat wave pushed temperatures into triple digits in many parts of state.

The wildfire burning near Shaver Lake exploded to 145 square kilometers, jumped a river and compromised the only road into the Mammoth Pool Campground, national forest spokesman Dan Tune said. At least 2,000 structures were threatened in the area about 467 kilometers north of Los Angeles.

The Fresno Fire Department tweeted late Saturday night that 63 people were rescued from the campground by military helicopters and that two of them were severely injured, 10 were moderately injured and 51 others had minor or no injuries.