(KMOV) -- Half a dozen people were hospitalized after a construction fire broke out outside the United States Post Office building in downtown St. Louis on Thursday.
Authorities say smoke vapors caused by the fire somehow got into the ventilation system of the post office on Market St.
The building was evacuated briefly while officials checked out the scene. Firefighters determined there was no danger and everyone was allowed back inside.
Officials say six people were transported to the hospital with non-life-threatening injuries. Sixteen others were treated at the scene.
The cause of the fire was unclear.