Commerce Street in Norwalk was shut down Wednesday afternoon because of an ammonia leak.
The leak was coming from the Crystal Ice Company on Commerce Street.
Workers reported a very strong presence of gas, fire officials said.
"The leak came from a valve on the roof of the ice company because of excess pressure in the system," fire officials said in a press release.
Streets around the area were closed, and Metro North trains that pass behind the company were slowed down.
Fire crews said the plant was shut down for the day while repairs are being made.
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