First responders are on the scene of a fire at one of two DTE plants in East China Township Thursday evening.
In an earlier statement, Detroit-based DTE Energy said air monitoring was in place and readings were "well within normal limits outside the facility perimeter".
Fire authorities said that the fire started in the plant's coal-powered generating unit.
DTE officials say a "generation unit" caught fire about 8 p.m. Fire crews worked through the night containing the fire that was finally completely extinguished by about 9 a.m. Friday.
There were no injuries from the blaze, which was reported about 6:30 p.m. Thursday.
When the St. Clair Power Plant will be back in operations is not clear, according to DTE.
Firefighters from across St. Clair County were called to the plant as thick, billowing black and grey smoke rose from the burning structure.
DTE customers are not expected to see any changes in their electric service.
The plant has been in service since 1953 and the utility said the facility has 294 employees overall.
Roads in the area have been closed and traffic is being detoured away from the plant.
A resident near the power plant said that this was the first time that she heard such noise from the plant.
"They blow the stacks occasionally, but this was unusually loud", she told the Times-Herald.
DTE Energy said late Friday afternoon that its access to the St. Clair Power Plant in East China Township in St. Clair County remains limited and that there is no estimate when the facility will reopen.
"There will be no job layoff or separation from this announcement; the workers will be transitioned to other DTE facilities", Brian Corbett, DTE spokesman, said in June. Units located in East China Township, Detroit, River Rouge and Trenton will retire between 2020 to 2023.