The Pacific Northwest was seeing steady heavy rainfall Tuesday as an unusually strong storm system called an atmospheric river passes through the region, according to the National Weather Service.

Fire crews rescued two people who were trapped by floodwaters at a campsite in the Gold Bar area of Snohomish County north of Seattle on Monday night, KOMO-TV reported. Crews used drones and water rescue crafts to reach them and get them to safety, officials said.

Gold Bar police said in a social media post Monday evening that deputies were going door-to-door in the Moonlight Drive neighborhood to warn residents of imminent flooding.

A mudslide closed eastbound Interstate 90 overnight at North Bend, about 30 miles (50 kilometers) east of Seattle, according to the Washington State Department of Transportation. Crews were expected to reassess the highway in daylight.

The weather service's Weather Prediction Center forecast several days of heavy rainfall in western Washington and northwestern Oregon with the trans-Pacific jet stream bringing heavy rain along the coast and more than a foot of new snow in the northern Rockies in northwestern Wyoming. Flood watches are in effect with scattered flash flooding possible along the coast and into the Cascades through midweek.

The weather service’s Seattle office said in a social media post on Tuesday morning that the atmospheric river shifted southward, but precipitation was expected to shift back northward later in the day, bringing another round of heavy rainfall and causing significant river flooding to continue.