Reportedly. This is the key word. It was also reported recently in Britain that 2,000 died during a cold snap. My wife is in the medical industry here and had a chance to question some of those numbers and the authors of the report admitted that almost all had died of something like heart attack or old age but they died during the cold week so the cold got tagged as an attibuting cause.
I don't believe for a minute that 14,000 people died because of the heat in France. The numbers were politically useful to Chirac to put pressure on the short work week and liberal vacation policies of the French health system. Without the 'disaster' it would be very hard to convince anyone to change what is- from their perspective- a good deal.
Americans readily believe the numbers because they hate the French. This is my opinion.