Last Updated Apr 26, 2018 1:03 PM EDT
SUPERIOR, Wis. — A tank containing crude oil or asphalt exploded at a large refinery in Wisconsin on Thursday, injuring several people and causing a blast that one worker described as sounding like a sonic boom.
No fatalities have been reported, but at least five people have been taken to hospitals in Duluth, Minnesota, following the explosion at the Husky Energy oil refinery at about 10 a.m., Superior Fire Chief Steve Panger said in a statement.
Panger didn’t have details about the extent of their injuries. Others were walking wounded.
A contractor who was inside the building told WDIO television that the explosion sounded like “a sonic boom” and that it happened when crews were working on shutting the plant down for repairs.
Panger said the fire was out by 11:20 a.m., although smoke could be seen rising from the plant. Panger said a small tank exploded containing either crude oil or asphalt.
Superior police are advising people to stay away from the area and roads around the refinery have been blocked off. There have been no neighborhood evacuations. Superior is a city of about 27,000 people that borders Minnesota to the north and the tip of Lake Superior.
No damage estimate was available. The Superior Fire Department sent all three engine companies to the explosion, and nearby Duluth sent over a command vehicle.
Calgary-Alberta-based Husky Energy refinery bought the refinery from Indianapolis-based Calumet Specialty Products Partners last year for over $490 million. It’s Wisconsin’s only refinery, and it produces gasoline, asphalt and other products.
The refinery, which dates back to the early 1950s, has a professing capacity of around 50,000 barrels per day and a storage capacity of 3.6 million barrels of crude and products. It processes both heavy crude from the Canadian tar sands in Alberta and lighter North Dakota Bakken crude.
© 2018 CBS Interactive Inc. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. The Associated Press contributed to this report.
