(CNN) -- The U.S. Army Corps of Engineers offered support Monday to state and local officials in western Washington battling fast-moving floodwaters and rising rivers.
Six teams, including 39 flood fighters, were sent to the Olympic Peninsula and the Chehalis, Nooksack, Skagit, Snohomish and Puyallup river basins to monitor areas of concern and provide real-time river condition observations to the local and federal emergency operations centers, officials said.
The Corps also supplied two pumps to the city of Orting at its request and 15,000 sandbags to Snohomish County.
Monday morning, the National Weather Service was reporting major flooding on the Snoqualmie River at Carnation and moderate flooding on the Snohomish River at Snohomish. Flooding also was occurring or was predicted for areas along the Green, Nooksack, Skagit, Skokomish and Chehalis rivers, according to the weather service's Advanced Hydrologic Prediction Service.
The Stillaguamish River, which Sunday evening rose to a record level at Arlington, had receded below flood stage Monday morning and will continue to drop, the prediction service said.
The rain that led to the flooding also triggered mudslides that shut down passenger trains north and south of Seattle over the weekend.
About 300 people are staying in shelters after homes flooded in several cities north of Seattle, said Rob Harper an emergency management spokesman for Washington. He said they evacuated voluntarily.
"Swift-water teams were called out Sunday," Harper said. "Rescue operations are still being mobilized to be available if needed."
Rivers in nine counties had crested at or above flood stage by Sunday morning, the state Emergency Operations Center reported. And a mudslide north of Vancouver, Washington, just across the state line from Portland, Oregon, shut down Amtrak's Cascades train route until Tuesday morning, Amtrak said.
"They have to make sure where the mudslide occurred or anywhere else along that track, that the slope is stable enough to where there will not be any chances of an additional mudslide occurring before they release passenger traffic back onto the track," said Washington Department of Transportation spokeswoman Vickie Sheehan.
Mudslides occurred north of Seattle as well, shutting down train service that connected the city to Canada, Sheehan said. But shutting down the Portland-to-Seattle run has "a much bigger impact that affects a lot more people," she said.
Amtrak will provide bus service for all ticketed passengers throughout the weekend and until the rail line reopens, Amtrak spokeswoman Vernae Graham said.
CNN's Antoinette Campbell, Jessica Jordan, Shelby Lin Erdman, Leslie Tripp and Greg Morrison contributed to this report.