Record temperatures have been causing mass poultry deaths in western France since June 22, Reuters reported.

The heat wave, with temperatures exceeding 40° Celsius (104° Fahrenheit), is also behind the drowning of 40 people. Météo-France, the French national weather service, wrote in a statement that June 24 and 25 were the hottest days recorded in France since records began in 1947.

Yann Nedelec, head of ANVOL, a French poultry-sector organization, estimated that at least several hundred thousand poultry in both indoor and outdoor farms died, though he told Reuters it was too soon for a precise death count.

Chicken farmer Clement Blanchard, based in Saint-Andre-Goule-d’Oie, a commune in Pays de la Loire, told Reuters that around 700 of his chickens had died over the span of a few days, compared to an average death rate of one or two per day.

“We’re faced with the same thing with our animals as we ​are ourselves: they suffer enormously from the heat, and so at times like this there are abnormally high death rates,” he told Reuters.