Fire department spokesman Kyle Moore says investigators determined Tuesday the fire was set and turned the case over to the police arson squad.
There were no serious injuries, but 10 people were displaced from the three older, wooden multiplexes in the city's lower Queen Anne neighborhood.
One of the buildings was destroyed and two damaged.
Moore says the fire was set in the garage, which didn't have a door and was full of materials that easily burned.
More Northwest Headlines
1 dead, 2 injured in drive-by shooting in Federal Way 8:09 a.m. Yakima youngsters mix Legos, science education Activists rappel off Oregon bridge to stop Shell icebreaker Stanwood man pleads guilty to stealing from Swinomish tribe Death penalty dropped from Carnation killings trial Poll: Just 30 percent inclined to re-elect Gov. Inslee GOP lawmakers want Washington to look at Planned Parenthood Salvation Army sets up charging ports for Portland homeless
Our new comment system is not supported in IE 7. Please upgrade your browser here.