The crash happened around 10:30 a.m. on NE Novelty Hill Road near the intersection of W. Snoqualmie Valley Rd. NE, just east of Redmond.
Video from Air 4 shows two sedans, a pickup truck and a dump truck were involved.
King County Sheriff's Deputies say two people were trapped inside and had to be freed, and video from the scene showed one person being loaded onto a stretcher, but none of the injuries were serious.
Novelty Hill Road will be closed for "some time," deputies said, as the dump truck is leaking fluid and it will take a while to clear the mangled wreckage.
No word yet what caused the crash.