This happens. Not too often, thankfully. The gear must have been red hot before catching fire. At least it wasn’t near the fuel tanks.
I wonder if the gear was locked? The pilots will always make certain that the landing gears are down and locked before landing. When the gears are down and locked, there are three green lights that come on to let the pilots know the gears are down and locked.
I had a flight where my nose gear wouldn’t lock, but just before landing we got lucky when it did finally lock.
I have questions about this incident. The NTSB will find out if they landed with an unlocked nose gear.
The article didn’t mention that they had declared an emergency.