On March 26, 1997, at about 3 p.m. an explosion occurred within a fuel blending tank at Chief Supply Corporation (Chief), in Haskell, Oklahoma. One worker was killed and two others injured. The explosion and resulting fire caused extensive damage to the facility. Several smaller explosions occurred as over 1,000 drums containing waste paints, oils, thinners, inks, cleaning solvents, assorted acids, bases, metal sludge, and four 5,000-gallon tanks holding waste fuels became involved in the fire. A highway next to the site was closed; the facility and an area 1.5 miles north and one mile east of the facility in the path of a large smoke plume were evacuated. The fire was fully extinguished three days later. Because of the severity of the consequences and the opportunity for lessons learned, EPA conducted a limited accident investigation to better understand and communicate the major causal factors contributing to this event. EPA's investigation focused on the fuel blending operations and characteristics of the substances involved.