"There was no lightning that could have caused the fire. So more than likely, it's human-caused," Rich Magnussen of the Chelan County Sheriff's Office said about the fire in and near the city of Wenatchee.
Authorities still are trying to determine the fire's exact cause and whether it was accidental or intentionally set, he said.
The fire has burned nearly 3,000 acres since it began Sunday afternoon
, officials said. It started outside Wenatchee but was burning within the city limits late Sunday night.
In addition to the homes, the fire has damaged four businesses or business complexes in downtown Wenatchee, said Nathan Rabe, the fire's incident management commander. The fire was 47% contained, he said Wednesday morning.
On Tuesday, about 4,000 homes were under a Level 1 evacuation order
, meaning residents should leave or be ready to leave at a moment's notice.
Officials are referring to the blaze as the Sleepy Hollow Fire, because it started on Sleepy Hollow Road.
The fire came as temperatures in the region topped 100 degrees, and rainfall has been scarce.
Wenatchee Mayor Frank Kuntz said Wednesday that he intended to sign an emergency declaration that would prohibit the use of fireworks in the city through the Fourth of July, citing the parched conditions.
The ban will not extend to two fireworks shows planned by professionals this weekend, he said.
The Sleepy Hollow Fire is one of four active wildfires in Washington, according to InciWeb
, an interagency incident reporting website.