Drone 12 captured the damage that showed flames destroyed the roof of the Quaker Bridge Road storage facility.
McCormick says the firefighter, who was not identified, was transported the Capital Health Hopewell.
Fire officials say several storage units were damaged in the fire that was contained to half of the building.
It was not immediately clear what sparked the blaze.
The fire remains under investigation by the Hamilton Fire Division, Hamilton Police Division as well as the Mercer County Prosecutor’s Office.