Manslaughter investigation after toddlers die in car during France heatwave

French police have launched an involuntary manslaughter investigation after two children, aged two and four, died in a car during Europe's record heatwave.

The children were found unconscious by their mother in the family's vehicle in Carpentras, southeast France, on Monday.

Initial findings suggest the siblings had locked themselves inside the car, and first responders were unable to resuscitate them.

The incident occurred amidst government warnings advising parents not to leave children unattended in vehicles due to the extreme temperatures.

Separately, France's Prime Minister reported that 40 people have drowned across the country in recent days while attempting to cool down from the heat.