French authorities had placed swathes of the country's southwest on orange alert for storms, and numerous areas were hit by power outages and transport chaos.
In the Aude department, officials cancelled the third stage of the Vuelta an Espana cycling race, which was being held in the area, when a hailstorm forced riders to seek shelter.
The tornado hit hardest in the village of Pomas, population 1,000, damaging an estimated 300 homes, in some cases ripping their roofs off.
More than 120 emergency workers were deployed to the scene, local authorities said.
Fifteen of the injured were taken to hospital.
They included a pregnant woman who was hurt when her house collapsed on her, her husband told AFP.
The national weather service, Meteo-France, said winds had reached up to 117 kilometers (73 miles) per hour in the nearby village of Arquettes-en-Val.
Storms across southern France upended the transportation network, delaying trains, forcing road closures, and causing delays and cancellations at airports in Bordeaux, Marseille, Nice, Toulouse and even Paris to the north, said Transport Minister Philippe Tabarot.
An estimated 2,800 homes were left without electricity across 10 villages, officials said.
France sees several dozen tornadoes per year on average.
The impact of global warming on their frequency and intensity is unclear, according to Meteo-France.