A hazardous materials team was dispatched to investigate what was initially an unknown leaking substance causing a fog inside a medical office building in Lake Forest Monday evening.
The Lake Forest Fire Department responded around 6:42 p.m. Monday to Northwestern Medicine Lake Forest Hospital McGaw Medical Building, 800 North Westmoreland Road.
Lake Forest Deputy Fire Chief Christopher Roberts said fire crews were initially sent to the scene after a fire alarm had been triggered in the building.
Firefighters investigated and found a fog in the basement of the building, which is located just south of Northwestern Medicine Lake Forest Hospital.
They evacuated the structure of occupants and backed out of the building while calling for additional resources, Roberts said.
Hazardous materials technicians and the MABAS 4 HazMat vehicle were dispatched. The Countryside, Highland Park, Lake Bluff, Libertyville, Lincolnshire-Riverwoods, Long Grove and Mundelein fire departments responded.
Fire crews donned hazardous materials gear and entered the building to investigate.
They found a cylinder leaking a substance that was believed to be refrigerant, Roberts said.
The area was ventilated after the cause was determined to be related to the HVAC system. No one reported feeling ill.
Roberts said the scene was turned over to the HVAC company that is responsible for maintenance on the campus.
Firefighters remained at the scene for three hours and cleared just before 10 p.m.