California's fire service reports that the wildfire in Yosemite National Park and surrounding areas has now burned 149,780 acres - an area larger than the city of Chicago.
Firefighters have been trying to bring the flames under control since last week but have only contained 15 percent of the fire.
NBC Bay area reports that 23 structures gave been burned, but that 4,500 are threatened.
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It comes after security was stepped up around the country following the Manchester Arena attack which killed 22 people.
A murderer nicknamed 'Houdini' after escaping the death penalty seven times has been given the lethal injection.
The distress signal sparked a police hunt in the area to find the person or group who made it.