TROUTDALE — A growing Oregon wildfire covered parts of Portland's metropolitan area Tuesday with ash and forced the shutdown of a lengthy stretch of highway through the state's scenic Columbia River Gorge.

It was one of dozens of wildfires burning in western U.S. states that sent smoke into cities from Seattle to Denver — prompting health warnings and cancellations of outdoor activities for children by many school districts.

The National Interagency Fire Center in Boise, Idaho, a federal agency that coordinates wildfire-fighting, said 80 large fires were burning on 2,200 square miles in nine Western states.

The 16-square mile fire east of Portland forced hundreds of home evacuations. Embers from the fire drifted in the air across the Columbia River — sparking blazes in neighboring Washington state.

The wildfire grew rapidly late Monday and overnight, giving authorities just minutes to warn residents on the Oregon side of the river to leave their homes. Authorities say they believe the blaze, which started Saturday, was caused by a 15-year-old boy and friends using fireworks. They've identified a suspect but have made no arrests.

A 30-miles section of Interstate 84 was closed in both directions because of thick smoke and falling ash and because flames reached the roadway in some spots, said Dave Thompson, a spokesman for Oregon's Department of Transportation.

"If it jumps the road, you'd be driving through a wall of flame," he said.

People in Oregon covered their faces to shield themselves from the smoke and the ashes falling on them.

"You can't really stand outside without getting rained on" by ash, said Joanna Fisher as she walked to work at a Troutdale, Oregon, naturopathic clinic with Calla Wanser, who was wearing a red bandanna around her mouth to keep the ash out of her lungs.

A fast-moving wildfire in northern Utah swept down a canyon Tuesday — destroying structures, forcing evacuations and closing highways.

A least five homes burned and more than 1,000 people were evacuated as high winds fed the flames in the canyon north of Salt Lake City. Thick black smoke closed parts of two highways as firefighters struggled to fight the blaze fueled by winds gusting at up to 40 mph.

Outside California's Yosemite National Park, a wind-fueled fire made its way deeper into a grove of 2,700-year-old giant sequoia trees on Labor Day. Officials said the fire had gone through about half the grove but had not killed any trees.

Giant sequoias are resilient and can withstand low-intensity fires. The blaze burned brush and left scorch marks on some big trees that survived, said Cheryl Chipman, a fire information officer.