I was parked next door to this when it happened, it was a Fiji Airways aircraft (737). 5 Fire Appliances turned up, as far as I could see there were NO pax on board at the time. The fireman accessed the rear hold and after quite a few minutes removed a black hard shell suit case that had quite a bit of smoke coming from it. The suitcase was placed on the tarmac away from the aircraft and sprayed with water for around 15 minutes before the smoke started to subside. Our pushback was delayed around 40 minutes waiting for the all clear from the fire authorities. Whilst this was happening PA's were being made in the terminal to try and identify the owner of the suitcase.
If this is yet Another case of a lithium ion battery going up then it just goes to show how lethal they are and perhaps the TOTAL lack of knowledge that the traveling public has about them.