No one was hurt.
Deputies were called to the area where Woodinville-Duvall Road intersects with Mink Rd. NE after drivers reported a man waving and pointing a gun at passing cars, said department spokesman William Akers.
When the first deputy arrived and found the man, the man repeatedly ignored commands and pulled out what appeared to be a black gun from his waistband, Akers said.
The man then raised the gun and the deputy fired several shots. The man was not hit but fell to the ground, at which time he was taken into custody, investigators said.
Police later determined it was a toy replica and the man is a resident of a nearby group home for developmentally disabled adults.
Deputies are still investigating the scene.
"We are grateful no one was injured in this dangerous situation," King Co Sheriff Steve Strachan said in a statement to the media.