The Superior Fire Department says there are no fatalities in the explosion at the Husky oil refinery, at least 5 Injuries have been reported. The explosion happened at about 10:06 a.m. at the refinery, which is in the city's East End. The nature of the casualties was not immediately disclosed.A contractor who was inside the building told Eyewitness News it sounded like "a sonic boom." He said crews were working on shutting the plant down for repairs. According to the contractor, that is one of the most dangerous times. Superior Police sent a message on Twitter asking people to stay away from the area. There is no evacuation of residents at this time. Roads are blocked off around the refinery, and employees have been evacuated.