Authorities say about 65,000 people have been displaced by the fires in Washington state.

US authorities have arrested a man on suspicion of arson in connection with the largest of three wildfires burning around the northwestern city of Spokane in Washington state, where tens of thousands of people have been forced to evacuate.

Aaron Farinacci, 37, was arrested on Monday in connection with the Old Trails fire and charged with first-degree arson. He is being held on a $1m bond after a witness allegedly saw him kneeling in grass where the fire is believed to have started, Spokane County Sheriff John Nowels told reporters on Monday.

The arrest came as firefighters continued battling blazes that have scorched large areas around Spokane, a city of about 230,000 people near the Idaho border.

The fires have burned a combined 8,026 acres (3,248 hectares), according to the federal interagency fire information system InciWeb. Officials said aerial assessments indicate between 700 and 1,110 structures have been destroyed since the fires erupted over the weekend.

Authorities said about 65,000 people have been displaced by the fires. No injuries have been reported, although officials are attempting to contact 14 people they have been unable to reach by mobile phone. Sheriff Nowels said they are not currently considered missing.

Scientists say human-caused climate change is increasing the frequency and intensity of wildfires by driving higher temperatures, prolonged drought and drier vegetation.

Daniel Swain, a climatologist at the University of California, Los Angeles, said eastern Washington had experienced one of its warmest winters on record, resulting in a severe snow drought that helped set the stage for this year’s fires.

“This is a recurring pattern we’re seeing now over and over and over again, starting in the second decade of the 21st century, and now continuing essentially every year,” Swain said during an online briefing.

Extreme heat and wildfire conditions are also affecting other parts of the world. Heat alerts remain in place across much of Japan, while South Korea recorded its hottest temperature on record. Wildfires have forced evacuations in parts of Greece and continue to threaten areas of Spain and France. Elsewhere, in North Africa, firefighters have also battled major blazes in Tunisia, Algeria and Morocco.