This happened on 29 of October in the Netherlands (in Ooltgensplaat to be more precise).
A crew of four was conducting routine maintenance to the 67 meter high turbine. They were in a gondola next to the turbine when a fire broke out. The fire quickly engulfed the only escape route (the stairs in the shaft), trapping two of the maintenance crew on top of the turbine. One of them jumped down and was found in a field next to the turbine. The other victim was found by a special firefighter team that ascended the turbine when the fire died down a bit. The cause of the fire is unknown, but is believed to be a short circuit.
Firefighters are fairly powerless to do anything to fight fires on wind turbines, and due to high costs maintenance crews have limited means and training to escape an emergency situation.
The tragedy in Ooltgensplaat has lead to a political inquiry ('kamervragen' in dutch) into safety precautions for wind turbine maintenance crews.
original link if anyone can translate it better:
Brand windmolen: 'Verlies collega's hartverscheurend' - Nieuws.nl