A powerful storm battered Washington state today, knocking out power to hundreds of thousands of people, disrupting road traffic and leaving at least two dead and two injured.

Winds should die down across the region by afternoon, but the storm has moved into California and forecasters say it will bring extreme rainfall by the end of the week.

A woman was killed Tuesday when a tree fell on a homeless encampment in Lynnwood, north of Seattle, local officials said. A second woman was killed near Seattle when a tree fell on her home, Bellevue officials said. Two people were injured when a tree fell on their trailer in Maple Valley, southeast of Seattle.

The storm with tropical storm force winds of 80 km per hour and gusts of about 110 km per hour felled trees and power lines overnight. More than 530,000 homes and businesses in Washington, Southwest Oregon and Northern California were without power, compared to more than 600,000 previously, according to Poweroutage.us.

The storm and heavy rain also damaged the power system in Canada’s Pacific coast province of British Columbia, knocking out power to about 225,000 customers Tuesday evening, provincial electricity supplier BC Hydro said. About 100,000 customers, mostly on Vancouver Island, were without power Wednesday morning.

An NBC affiliate in Seattle broadcast images of cars destroyed by fallen trees and damaged homes.

The Snohomish Regional Fire and Rescue Service in western Washington urged residents to stay home as many trees and power lines were down.

“Trees are falling and falling on homes all over the city,” the Bellevue Fire Department posted on social media. “If you can, go to the lowest floor and stay away from windows. Don’t go outside if you can avoid it.”

Schools in western Washington today canceled classes or postponed the start of school.

“The storm is just getting started,” said Rich Otto, a meteorologist at the National Weather Service’s Weather Prediction Center in College Park, Maryland.

“We haven’t had much rain yet, only 2 to 3 inches over southwestern Oregon and northern California,” Otto said.

‘BOMB CYCLONE’ The storm, called a “bomb cyclone” when it rapidly intensifies, will linger over Northern California for the next few days, Otto said. On Friday, rainfall could reach up to 20 inches (51 cm) in parts of southwestern Oregon and northern California, Otto said.

A bomb cyclone intensifies rapidly in 24 hours or less when a cold air mass from the Arctic collides with warm tropical air in a process meteorologists call bombogenesis.

The weather service has issued warnings and warnings for high winds and flooding, including snowstorm warnings, across the U.S. Pacific Northwest, from northern Washington to the Sierra Nevada Range.

Washington state’s transportation department warned motorists to use caution on roadways as downed trees and weather slowed traffic across the state.