Crews were called to the scene of the Dana Farber/South Shore Hospital Cancer Center in Weymouth.
Fire officials say crews arrived shortly before 11:30 a.m. Monday but didn’t see any smoke or fire from the exterior.
However, once inside the building they found a haze or smoke condition in the mechanical area of the fourth floor.
Additional resources were called to the scene and the building was evacuated.
It was then discovered that a pipe in the mechanical room had cracked releasing refrigerant gas.
Officials say there was no fire or issue with the air handling systems.
A ventilation fan was used to remove refrigerant gas that had been contained in a stairwell and all floors were checked to ensure there was no remaining hazard.
The center was closed until an air quality test could be performed.
One firefighter was transported to South Shore Hospital for heat exhaustion, then released, while South Shore EMS provided rehab for firefighters working at the scene.
Quincy, Rockland, and Randolph provided mutual aid.
