Three fire engines are currently at the scene between Peterhead and Fraserburgh.
A Scottish Fire and Rescue spokesman confirmed the call came in at 2.25pm this afternoon.
Two fire appliances were called from Peterhead and one from Fraserburgh.
Crews are using two hose reel jets and six breathing apparatus.
A spokeswoman for Stagecoach Bluebird said: “We are currently assisting the emergency services with an incident on service 69, in Crimond.
“Our driver is safe and well, as are the few passengers who were on board. Safety is our absolute priority and we will carry out our own investigation to the cause of the incident.”
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