Two appliances and crews from West Ashland, one from Broughton, one command support unit from Olney, along with three officers attended.
The firefighters used two hose reel jets, one main jet, a 10.5 metre ladder, lighting and a thermal imaging camera.
They also isolated the gas and electric supply.
Thames Valley Police also attended, a scene guard is set to remain in place.
Crews also reinspected the building at approximately 6 am to check for hot spots.