UPDATE: The Salem Fire and EMS Department's Fire Marshal has determined the fire was caused by improperly discarded smoking materials.
The damage from the fire is estimated to be approximately $600,000.
The entire building sustained heavy fire damage throughout the second and third floors and the majority of the building suffered water damage.
It took crews more than two hours to contain the blaze and several more hours to extinguish the fire, according to Salem Fire and EMS.
Crews from Roanoke, Roanoke County, and Salem are working to fight the fire in the Mount Regis Center Outpatient Building.
All 21 patients were evacuated safely, and fire crews are checking them for any signs of smoke inhalation.
The building was built in 1914, and crews say, because of its age, it burned quickly.
Crews are still investigation to determine what caused the fire to start.
The Mount Regis Center says it is working with sister facilities to find housing for the displaced patients.
SALEM (WSLS 10) - Emergency crews respond to a fire late Saturday night in Salem.
The fire is at the Mount Regis Center on Kimball Avenue.
We have a team on scene and are working to get more information.
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