On 28 July 2013, with passengers still boarding an Air France Boeing 777-300, an abnormal 'burnt' smell was detected by the crew and then thin smoke appeared in the cabin. A MAYDAY was declared and the Captain made a PA telling the cabin crew to evacuate the passengers via the doors, only via the doors. The resulting evacuation process was confused but eventually completed. The Investigation attributed the confused evacuation to the way it had been ordered and established that a fault in the APU had caused the smoke and fumes which had the potential to be toxic.