Jeff Barnard / The Associated Press

GRANTS PASS — East winds helped spread a wildfire in the Columbia River Gorge on Wednesday as it burned a fourth house and pushed into the Mount Hood National Forest, fire officials said.

The Government Flat Complex has burned across more than 13 square miles in an area 10 miles southwest of The Dalles, fire spokesman Justin de Ruyter said. It was 15 percent contained.

A fourth home and two more outbuildings burned Wednesday. Nine outbuildings have burned since the fire started Aug. 16.

Fire crews attacked by air and ground on Wednesday afternoon as the aggressive Blackburn Fire, part of the complex, spread to the north and west.

Spot fires were seen as far as a quarter mile ahead of the fire front, officials said.

Ash was falling and skies were smoky in portions of Hood River County and western Wasco County. Fire officials say such conditions are temporary and may extend several miles downwind of an active wildfire.

Mandatory evacuation notices have been lifted. However, fire spokesman David Morman said late Wednesday that residents of about 75 homes have been told to be ready to leave if necessary.

The owners of many of the threatened homes scattered through rugged canyons covered in trees and brush have not cleared fuel from around the buildings and roads leading to them, making it tough for firefighters to save them, deRuyter said.

“It happens every year,” he said.

Ranked as the top priority fire in Oregon and Washington — and fourth in the nation — the fire continues to get new personnel despite a crunch on nationwide firefighting resources. More than 800 firefighters and support personnel are on scene. The cost has gone over $3 million after five days. Three National Guard helicopters joined the fight, bringing air resources to nine helicopters. Two structural task forces that had been protecting homes were released, leaving four on the fire.

Two smaller fires in the complex were under control, de Ruyter said.