At least one person was killed and two people were injured by falling trees in Washington Tuesday evening as an atmospheric river brought strong winds to the Pacific Northwest, knocking out power to many.

A woman in her 50s was killed in Lynwood after a tree fell on a homeless encampment, South County Fire said on Facebook. In Puget Sound, two people were taken to hospitals when a tree fell on a trailer.

“One patient was extricated in a short time. It took firefighters an hour to free the second patient,” Puget Sound Fire said.

About 650,000 customers in Washington were without power just after midnight, according to Poweroutage.us, a site that tracks energy providers. The majority of the outages occurred in Snohomish County and King County, which includes Seattle.

A massive plume of moisture from the Pacific Ocean, called an atmospheric river, hit the West Coast Tuesday afternoon and is expected to last until Friday. The storm is expected to become a bomb cyclone, meaning the pressure at the center of the storm will drop by 24 millibars within 24 hours.

The storm could be so strong that it drops almost double that speed, which amounts to more than 40 millibars in 24 hours.

Max Golembo and Emily Shapiro of ABC News contributed to this report.