Wildfires have burned through a record number of acres in California this year as firefighters continue to battle several large blazes across the state.

The state’s department of forestry and fire protection, Cal Fire, says more than two million acres have burned, more than the size of Delaware. One fire, El Dorado, which has spread over 7,000 acres, was started by a gender reveal party, officials say. California is currently experiencing a record heatwave.

Los Angeles County reported its highest ever temperature of 49.4C (121F) on Sunday. Although temperatures are expected to drop from Tuesday onwards it may bring strong winds which could fan the flames, the National Weather Service warns. More than 14,000 firefighters continue to battle 24 fires across the state, Cal Fire said.

The largest blaze, known as the Creek Fire, has burned more than 78,000 acres since it broke out in the Sierra Mountains on Friday, and the authorities said none of it had been contained.

The fire has burned at least two dozen dwellings in the town of Big Creek, the Los Angeles Times reports. More than 200 hikers had to be airlifted out of the popular Mammoth Pool Reservoir after becoming trapped by flames on Saturday.