Two people were injured and taken to the burn unit at Bridgeport Hospital after a fire at a plating company in Meriden on Monday.
As of Tuesday morning, one patient is critical and one is fair, according to hospital officials.
Crews responded to CRC Chrome at 169 Pratt Street in Meriden around 10:50 a.m. after getting a report of an industrial injury and found a working fire.
Officials said the fire was contained, but was burning inside the walls of the building and would take some time to put out.
There are chemicals in the building, which fire officials were concerned about, and firefighters were cautious about using water because they don't know what chemicals might react or how they would react, the fire chief said.
When the fire broke out, the building was occupied, authorities said.
Employees at the company dumped lacquer into a heated rinse tank that cause a reaction that flashed over the sides of the tank, injuring two employees, according to the Department of Energy and Environmental protection.
The flashover also caused the roof to catch fire.
The two people who were injured were transferred to the burn unit at Bridgeport Hospital to be evaluated, according to fire officials.
Mutual aid was brought in from several departments to fight the fire and cover the rest of the city. Hazmat crews were also been called in, officials added.