Fast-moving fires left a trail of destruction in the northwestern US city of Spokane on Sunday, with officials reporting hundreds of structures reduced to cinders.

Thousands of people were ordered to evacuate their homes on Saturday and overnight into Sunday, as three separate fires broke out in and around the city in the east of Washington state.

The National Weather Service (NWS) had warned of "extremely critical fire weather conditions" in the area due to strong winds and exceptional dryness.

Video posted online and by local media on Sunday showed scores of homes burned to the ground, with heavy smoke still blanketing the city.

"Hundreds of homes and structures have been lost. We are still assessing the potential for lives to be lost," Mayor Lisa Brown told a press briefing on Sunday.

"To the people who are suffering right now in our region from either loss or uncertainty... our hearts go out to you. We are here for you for the long term," she said.

Weather conditions had improved on Sunday, with wind dying down, but the fires were still listed zero percent contained.

Sheriff John Nowels said no deaths or injuries had so far been reported, but "because of the scale of this and what it takes to... do those kinds of investigations in an active fire scene, that could change."

Washington Governor Bob Ferguson, who declared a state of emergency, noted that the state is enduring a fourth consecutive year of drought as climate change creates conditions conducive to destructive wildfires.

He told the press conference that he had spoken to federal officials about receiving resources to respond to the disaster, including US President Donald Trump, who understood "how dire the situation is."

The head of Washington's Department of Natural Resources, David Upthegrove, warned that the fire in Spokane was "one of 15 major fires burning throughout the state of Washington right now."

"This is an extraordinary wildfire season in the Pacific Northwest. It's not a normal season," he said.

"A confluence of weather conditions, a confluence of fires throughout the West, are stretching our resources and challenging the individuals in this response."

The biggest of the three fires burning in Spokane, the Old Trails fire, jumped the Spokane River on Saturday afternoon and crossed into the city proper.

Authorities issued the highest-level evacuation alert, "Go Now," for swathes of northern Spokane affecting thousands of people within city limits, according to the government's evacuation map.

As of Sunday morning the three fires had charred a total of 5,390 acres, CNN reported.

Emergency authorities set up a fire evacuation shelter at the Spokane Convention Centre. (AFP)



Edited by Cecil Wong