More than 50 people have been rescued from flooded areas in eastern Oregon since Thursday, authorities said.
Parts of Umatilla County have experienced significant flooding since Thursday, leaving many residents trapped in their homes or vehicles.
Umatilla County Sheriff Terry Rowan said the flooding progressed rapidly, washing out bridges and roads and making access for residents and emergency personnel difficult.
On Friday, Gov. Kate Brown declared a state of emergency in Umatilla, Union, and Wallowa counties due to the severe flooding conditions.
"We've had two days of rain," said Kevin Jeffries, a spokesman for the Umatilla County Joint Information Center. "Usually it's snow this time of year."
The rain created a massive snow melt in the mountains leading to "some pretty wild flooding," Jeffries added.
Several helicopter crews rescued dozens of residents and continue searching for flooding evacuees on Saturday.
As of Saturday, no deaths or major injuries were reported.