The incident took place in Norwalk around 2:50 p.m., Thursday, April 13 at a warehouse building located at 16 Muller Ave.
The initial call was for an explosion with a chemical release, said Timothy Reardon, deputy chief of the Norwalk Fire Department.
Upon arrival, firefighters determined all workers had self-evacuated the building. Explosive and toxic vapors were found within the building in a confined area, Reardon said.
"Rescue 2 and the Department of Energy and Environmental Conservation worked together to mitigate the hazard," he said.
The "product" (or toxic fumes ) was released from a medium-sized tank that was located in a storage room. The incident was controlled within two hours by 15 firefighters, officials said.
Norwalk EMS assessed four workers for inhalation injuries, Reardon said. There were no reported injuries to firefighters.
The Norwalk Fire Marshal Division and DEEP are investigating the incident
Click here to follow Daily Voice Trumbull-Monroe and receive free news updates.