First responders were called to the Tonawanda Coke plant shortly before noon Friday in response to calls of an "explosive" sound. Tonawanda police says the sound was heard in a wide area of the town.
According to a statement, there was a minor explosion and small fire at the River Road plant. Company officials say all safety systems worked as designed, and the situation was quickly brought under control.
There were no injuries. Officials say there were no release of toxins.
But the Clean Air Coalition is calling on environmental regulators to investigate what happened and to make sure the public was not harmed by emissions.