We'd come in by the Eurostar to Gare du Nord, and trundled our cases round the corner to Gare de l'Est, where we used the left luggage office. On the way, we had passed a half dozen burnt-out cars.
Walking out of the front of the station, we then saw a full scale incident, with lots of flashing lights, and a fire tender with ladder raised and the fireman at its tip squirting a rather large hose in through a high window, out of which billowed large amounts of smoke.
I understand that some people call Paris 'the city of lights'. Basic observation shows them to be mistaken - it's the city of fires.