A wave of residents returned to their southern California mountain communities following a week of wildfires that have killed 20 people and destroyed more than 3,400 homes.

Arsonists are to blame for at least three of the raging fires in southern California that have so far claimed the lives of 20 people and destroyed more than 2,600 homes, authorities said.

Firefighters struggled desperately to save emptied-out resort towns in southern California’s San Bernardino Mountains as 200ft walls of flame engulfed dead and dried-out trees.