In a tweet, the National Weather Service said some smoke had blown east to Phoenix, Arizona - nearly 300 miles (482km) away

It has since stretched out to 20,516 acres (8,302 hectares), San Bernadino National Forest said in a tweet on Sunday

The government body said the blaze had been fuelled by high temperatures, low humidity and dry vegetation in the area

The US Forest Service told the Riverside Press-Enterprise, a local newspaper, that because the fire was on rugged terrain, it was dangerous for firefighters to try and surround it

"We don't want to put fire-fighters in a dangerous situation," said spokesperson Lisa Cox