Employees were trying to thaw and open a frozen valve on a tanker. The tanker truck engine was running in the shop. One employee vented the tank and released volatile hydrocarbons, causing the engine to run away and catch fire. Other volatiles exploded, blowing the building apart and igniting the tanker engine. The injured employee had just started to run out of the building when the explosion happened. The force of the explosion caused the employee to be thrown approximately 20 feet from the building, landing on the frozen ground. The employee suffered burns to the face and hands, rib fractures, and a collapsed lung.