The Mashpee, Massachusetts, HAZMAT team responded to a call at the Franey Medical Labs on Mercantile Way Saturday morning.
There were reportedly lower levels of carbon monoxide and a decreased level of oxygen. There was also a distinct odor.
The cause is unknown at this time.
The fire department and HAZMAT officials ventilated the structure. Everyone self-evacuated the building safely.
There were only three employees inside the building when the event occurred.
One of the employees was taken to Falmouth Hospital for evaluations after complaining of a headache.
The scene is now clear.