Air quality is improving around the site of Thursday's explosion and fire at the Husky Energy refinery in Superior.
However, Fire Chief Steve Panger says the immediate area of Thursday's fire at the Husky Energy refinery remains extremely hot.
"I can see black billowing smoke, and it's lingering in the sky", said Bunny Vidotto, who lives in Superior, WI and is originally from Thunder Bay, Ont., in an interview with CBC News on Thursday.
In Duluth, St. Luke's Hospital was treating one person and did not expect to receive any more, spokeswoman Jessica Stauber said.
Local press have reported that the initial blaze was put out by 11:20 am but after a series of follow-on blasts it took until 18:45 to declare the fires onsite fully extinguished. The seriously hurt worker suffered what has been described as a blast injury.
Residents are still not in their homes after a smoky refinery fire forced most of their northwestern Wisconsin community to evacuate.
Officials ordered an evacuation of a wide area around the Husky Energy refinery to reduce the public's exposure to the plume.More news: Jose Mourinho sends Arsene Wenger a classy tribute ahead of last meeting
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Calgary-Alberta-based Husky Energy refinery bought the refinery from Indianapolis-based Calumet Specialty Products Partners previous year for over $490 million. Schools in Superior and nearby Maple, Wisconsin, canceled classes Friday as a precaution.
A contractor who was inside the building told WDIO television that the explosion sounded like "a sonic boom" that happened when crews were working on shutting the plant down for repairs. The DNR, EPA and the Superior refinery will continue to monitor the situation for any possible changes.
The refinery, built in 1950, employs about 180 people in the production of gasoline, diesel fuel, motor oils and asphalt, according to the U.S. Energy Information Administration.
Essentia Health says its hospitals and care facilities in the area cared for 16 patients as a result of the incident.
In 2015, when Calumet was owner, OSHA issued four citations to the refinery, three of them for serious violations involving flammable and combustible liquids, hazardous waste operations and emergency response.
Husky purchased the refinery from Calumet Specialty Products Partners LP previous year.