By David Schwartz and Andrew Hay

Over 1,500 residents fled small communities in mountains about 50 miles (80 km) northeast of Phoenix, Arizona, as a wildfire grew to an area larger than the city of Detroit overnight, fire officials reported.

Firefighters battling the Bush Fire faced gusting winds, low relative humidity and triple-digit temperatures as flames leaped through piñon pine and juniper in the Tonto National Forest.

The fire, which began with a vehicle blaze, was the largest of 37 fires burning in the United States at 114,941 acres (46,515 hectares) and already the seventh largest in Arizona history, according to National Interagency Fire Center (NIFC) and National Weather Service (NWS) data.

“We have hotter temperatures approaching,” said Marvin Percha, a meteorologist at the National Weather Service in Phoenix, forecasting above-average temperatures of 110 degrees Fahrenheit (43 Celsius) by Monday.

Around a dozen other fires burned in Arizona as it faced another record daily rise in coronavirus cases on Thursday.

The Mangum Fire had blackened 56,780 acres (22,980 hectares) around 40 miles (65 km) north of the Grand Canyon, forcing 230 people to leave their homes. Four hundred homes were evacuated for the Bighorn Fire north of Tucson, which had burned 23,892 acres (9,669 hectares).

To the west, much of California remained under a “red flag warning” for erratic gusty winds, around half a dozen small fires burning up and down the state.

Alaska reported dozens of small blazes and the use of dogs to protect wildland firefighters from bears. Karelian Bear Dogs, a Finnish breed known for their fearless nature, were flown to a firefighting camp to protect personnel and supplies from the intruding animals, according to fire authorities. (Reporting by Andrew Hay in Cañon, New Mexico, additional reporting by David Schwartz in Phoenix and Yereth Rosen in Alaska New Mexico; Editing by Jonathan Oatis)