The fire station, which housed Ladder 2 -- better known as the "Ben Franklin" fire house for its location in the city's historic neighborhood -- will have to be closed, WCAU-TV, Philadelphia, reported Saturday.
It wasn't immediately clear what caused the fire in the ambulance, parked in the hall's garage.
When firefighters returned from the call they found their hall in flames. It took them about 10 minutes to get the fire under control, officials said.
A union representative said budget cuts left firefighters without a critical pumper truck that could would have been used if it had been available. City officials disputed the union's claim, noting because the firefighters were away when the blaze started it probably wouldn't have made a difference in saving the structure.