Indigo catches fire upon landing in Nepal

[Old King Coal]

I would suspect the sequence went like this:

1. The aircraft landed in Kathmandu.
2. It was maybe at its maximum Performance Limited Landing Weight, e.g. perhaps due to tankering fuel into KTM (which is a regular practice by most airlines - mine included - due to the price of fuel at KTM) and which (along with 1, above) requires a high-level of braking in order to stop the aircraft on the runway (and especially so if they were to float / land 'deep'), and therein the brakes would get v.hot. Nb. It takes a couple of minutes for the heat in the brakes to build-up to the point where they cause a problem with the tyres.
3. The aircraft vacated the runway, and taxied for a couple of minutes (see closing comments in 2 above) to its parking position on the ramp.
4. The ramp crew are waiting at the parking position, ready to apply chocks, steps, baggage handling equipment, catering, honey-truck, etc... (which is why lots of ramp equipment can be seen in the video)
5. The brakes are set and the seatbelt sign is switched off (the crew, at this stage, do not have any indication of anything being wrong... aside, perhaps, from the brake temp sensors suggesting that the temps on brakes 3 & 4 are 'high'; albeit that's assuming that such sensor are fitted?).
6. The passengers leave their seats, begin removing their belongings from the overhead lockers. They are now standing in the aisle, with their hands full of their belongings, and are anticipating leaving the aircraft via normal means (i.e. via the steps).
7. At about this time, a "Fire!" at the right main gear is reported to the flight crew.
8. The Captain initiates an evacuation over the PA.
9. As part of initiating an emergency evacuation, the Cabin Crew would first check that the outside areas are clear of obstructions before opening the doors (and therein blowing the slides... always assuming that the slides were still armed, remembering that they had just pulled onto stand and that the normal sequence is for the Cabin Crew to disarm the doors). However, on the left side of the aircraft there are passenger steps now in the way, and thus they can only open the doors on the right hand side.
10. The eagle-eyed might also notice that the flaps are not set (down), i.e. for the passengers to slide down, if they're evacuating via the over-wing exits. That would most certainly be due to a lack of hydraulic power; what with the engines having been shutdown and / or the electric hydraulic pumps (which would be slow to run in any case) having been switched off (as part of the normal on-chocks shutdown sequence) and which the flight crew had probably completed, i.e. prior to being told about a 'fire'.

So, for those bemoaning that the passengers were evacuating with their baggage in their hand, if given the above as possible sequence of events, it is highly understandable and / or indeed highly likely that the pax would indeed evacuate the aircraft with their belongings in their hand, and it is probably better that they did so (rather than dropping their baggage into the aisle and therein cluttering it up... remembering that neither the passengers or crew were expecting or anticipating an emergency evacuation at that particular point in the proceedings).

This sort of event is most certainly a tricky one to deal with, i.e. an unplanned emergency evacuation (due to a 'fire'); occurring on the parking bay; with poor or little or no communications with the ground crew (aside from them doing a lot of hand waving and head-wobbling); with no hydraulic power available (to move the flaps); with ground handling equipment being pulled into position around the outside of the aircraft; with the passengers in the process of getting ready to the leave the aircraft (along with their cabin baggage); with the doors disarmed; etc, etc...

Note to self: this is is an excellent scenario to add to ones armoury for the simulator !

Dramatic evacuation after Indigo plane catches fire - YouTube