Four workers were injured in an industrial accident at the BP Whiting Refinery on Friday.
BP spokesman Michael Adbendhoff said the extent of the oil workers' injuries and their conditions were not immediately known.
The injuries, however, were serious enough that they had to be taken by ambulance to local hospitals.
"BP regrets to report that four individuals have been transported to local hospitals as a result of an incident at a power distribution center inside of the refinery," the company said in a statement. "Our primary concern is to help ensure the injured employees receive the care they need. There has been no other impact to the environment or the local community."
BP had no further details about what the incident was, or how it happened.
Whiting Mayor Joe Stahura said the Whiting Fire Department was not called out and the refinery responded to the accident internally with its own in-house fire department, which is not uncommon. The incident had no impact on the city outside the refinery gates, he said.
"Our concern is with the guys who were hurt," he said.
Dave Danko, president of United Steelworkers Local 7-1, which represents more than 1,100 oil workers at the refinery, did not immediately respond to messages.
The injuries at the BP Whiting Refinery took place on Worker's Memorial Day, when hundreds of local USW chapters across the country were calling for improvements in workplace safety, conducting training sessions, and highlighting how accidents are often preventable at ceremonies recognizing workers who were killed or injured on the job. It's an annual day of observance that takes place April 28.
The BP Whiting Refinery, which has tank farms that spill into neighboring Hammond and East Chicago, employs more than 1,800 workers and often has hundreds of union contractors working there on maintenance projects. It converts crude oil from Canada and the Dakotas into gasoline that's sold in seven states across the Midwest, and is the largest refinery in the Midwest.