It was nothing particularly serious from a safety standpoint.

It was not a fire, but an engine surge. Engine surges look like fires to a layperson, but they are not. The flame is not sustained -- just a one time thing. Engine surges are fairly routine events -- rarely a day goes by without one being reported somewhere in the world.

It is large economic issue, however. The aircraft in question is currently AOG at JFK, but a replacement engine is scheduled to arrive today. The engine that surged will need to be overhauled (I cannot go into the specifics of what the damage is).