Updated with new information at 6:53 p.m.
Five workers were injured in a propane explosion at a construction site north of Edmonds Thursday morning. Damage from the blast is expected to total at least $1 million, including the two buildings under construction, building materials, the propane tank and truck, and a construction trailer.
All five injured workers were inside the larger of the two buildings,said Leslie Hynes, public information officer for Snohomish County Fire District 1. The propane explosion had a blast zone with a 300-foot radius, and the blast extended into both buildings. Fire investigators believe there was most likely a second explosion inside the building where the injured employees were working, Hynes said, and the explosion occurred when flames from the propane explosion ripped through the building and ignited flammable vapors from a painting process.
The blast was reported at 11:10 a.m. in the 6300 block of Picnic Point Road, where workers are building a wastewater treatment plant for Alderwood Water and Wastewater District. Contractors estimated about 60 workers were at the site when the explosion occurred as a 1,000-gallon propane tank was being loaded onto a truck to be removed from the site.
“About 300 gallons of propane remained in the tank. The tank shifted during the loading process and a valve snapped, expelling the propane,” Hynes said. “The truck driver told firefighters he yelled for everyone to get away from the truck, but the propane immediately ignited and exploded.”
Two of the five workers injured in the blast sustained injuries that appeared to be life-threatening, Hynes said. All five workers were transported by paramedics to Harborview Medical Center in Seattle. Four were admitted and one has been released.
More than 50 firefighters from Fire Districts 1 and 7, Lynnwood, Mukilteo and Snohomish County Airport Fire departments responded. “The propane tank, truck and the ground surrounding it were in flames when firefighters arrived. An adjacent construction trailer was burning. We also had fires in two two-story buildings that are under construction,” Hynes said.
Firefighters had the fires under control by about 1 p.m., but crews continued to battle small brush fires in a wooded area behind the site throughout the afternoon.
The Snohomish County Fire Marshal’s Office is investigating the fire.
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