Firefighters swarmed into northwestern Spokane County Friday evening to fight a blaze that grew quickly, sent a large plume of smoke into the air and sent embers into yards across Long Lake.

Triple-digit temperatures and low humidity helped the fire, which started near the 28000 block of West Long Lake Road around 5 p.m. Friday, grow to 400 acres by 8:30 p.m.

Early estimates that the fire, just south of Long Lake, reached 600-700 acres may have been skewed by the heavy smoke, Department of Natural Resources spokesman Guy Gifford said.

“We are making good progress,” he said late Friday. “It’s not running as quickly as before.”

Firefighters were putting a dozer line around the south end of the fire, and the flames stopped at Long Lake – the Spokane River – on the north side, Gifford said. The fire was approaching irrigated fields to the east. “We’re looking to stop it at the fields,” he said.

Residents between the 23000 and 28000 blocks of Long Lake Road were under a Level 3 evacuation notice, which means they have been urged to leave, but that was expected to be lifted late Friday evening.

About 16 homes were threatened. One structure burned, but Gifford said he didn’t know if it was a home or an outbuilding. Multiple agencies responded, including five water tankers and five helicopters.

“Pretty much everyone in Spokane County has sent resources,” Gifford said.

Gifford said people reported falling embers that created spot fires. There was an unstable air system in place that allowed the smoke column to go high in the air and create a chimney effect, Gifford said, which sucks embers from the fire that can drop more than a mile away.

Therese Lally lives in Nine Mile Falls, across the Spokane River from the fire. As she sat on her deck Friday evening, she noticed embers beginning to fall in her yard. “There was one that was the size of a quarter,” she said.

Lally and her husband discussed watering down their roof.

“I’ve got my sprinkler on right now because of it,” she said Friday evening. “The roof I’m a little worried about.”

She said she hoped the fire would be stopped by the river.

“It’s pretty thick smoke,” she said. “The sky is orange. It’s creepy.”

Stevens County Fire District 1, which covers the area just north of Long Lake, brought on extra crews to patrol their side of the lake to look for spot fires.