The single-engine Cessna 172 crashed just after 2 a.m. into Mount Si, a 4,200-foot mountain 30 miles east of Seattle, Sheriff's Sgt. Cindi West told KOMO-TV, Seattle.
She said nearby residents called police reporting they heard a "sputter, pop and an explosion" from what sounded like a low-flying plane, The Seattle Times reported.
Authorities located the wreckage through the plane's emergency beacon at about 7:30 a.m. and recovered the bodies of a woman and two men, whose names were not reported, KOMO reported. The flight route of the plane has not been released by authorities.