1 dead from falling tree as storm hits Washington, knocking out power for 650,000

At least one person was killed and 2 people were injured by falling trees in Washington Tuesday night, as an atmospheric river carried strong winds into the Pacific Northwest, knocking out power to many.

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

"One patient was extricated in a short period of time. It took firefighters an hour to extricate 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 tracking energy providers. The majority of the outages were in Snohomish County and King County, which includes Seattle.

A massive plume of moisture from the Pacific called an atmospheric river hit the West Coast on Tuesday afternoon and is expected to last into Friday. The storm is expected to become a bomb cyclone -- which means the pressure in the center of the storm will drop 24 millibars within 24 hours.

The storm could be so strong that it even drops close to double that rate -- meaning more than 40 millibars in 24 hours.

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