A 28-year-old woman and a man in his 30s suffered burns on the upper parts of their bodies Sunday after the marina's "J" dock caught fire, KIRO-TV, Seattle, Wash., reported Monday.
The victims, whose names were not reported, were taken to Harborview Medical Center.
Assistant Chief Gordie Olson of South King Fire and Rescue said the woman and man were working on their boat when the fire quickly broke out and spread to other vessels.
Where or how the fire started was not reported.
Seven fire departments were called to fight the flames, KIRO reported.
Olson said booms would be brought in to contain any fuel that may have leaked into the water from burned boats.