MUKILTEO, Wash. (AP) - The fire department estimates property damage at $1 million from a propane tank explosion during construction work at a water treatment plant near Mukilteo.

Snohomish County Fire District 1 says the explosion Thursday left a 300-foot blast zone that damaged two buildings, building materials and a truck and trailer.

Five inured people were taken to Harborview Medical Center in Seattle. One was treated and released; three were in satisfactory condition Thursday night, and one critical.

Fire department spokeswoman Leslie Hynes says workers were moving a tank with about 300 gallons of propane inside when a valve broke off. Workers were running away when the propane ignited in the explosion.

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