Emergency crews attended Candleford Court at just before 4pm this afternoon.
UPDATE (21:15pm)
High levels of carbon monoxide levels were detected in the building, causing the mass evacuation.
One appliance and crew from Buckingham, one from West Ashland, one from Brackley and two officers attended, and were at the scene for about four hours.
Firefighters used gas monitors, breathing apparatus and fans and assisted with the temporary evacuation of residents from about 100 flats.
The high carbon monoxide levels were caused by generators in the previously flooded basement car parks. A phased return of residents to their flats began early this evening.
Thames Valley Police, Buckinghamshire Council, South Central Ambulance Service and its Hazardous Area Response Team also attended.
EARLIER:
Police have closed a road in Buckingham, with emergency services on the scene.
Police, ambulance and the fire brigade are all in attendance at Bridge Street (7:30pm)
At this stage it's unclear what the incident is, but this is a developing story and we'll have more when it's available.