Hall told reporters Monday that all 7 members of the team working on the naphtha hydrotreater unit were within 50 feet of the source of ignition, adding that none had any chance to escape.
The Skagit Coroner's Office said the 3 men who died at the scene died from the inhalation of toxic products of combustion and from thermal injuries to their entire bodies. Two other workers died within hours of the fire. Two other employees were badly burned and are being treated at Harborview Medical Center in Seattle.
Hall said the investigation by his team could take as long as 18 months because of the time needed to deconstruct the area where the fire occurred, conduct tests and compile refinery data and compile statements.
The state Department of Labot & Industries is also investigating the accident.