A 72-year-old victim was seriously injured when a gust of wind lifted the marquee into the air sent it crashing into the crowd of 300-400 people, many of them senior citizens, in the eastern French town of Joinville.
Joinville is in Haute-Marne department, which had been on yellow alert for bad weather at the time. Had the alert status been higher, as it was in some neighboring departments, the dance would have been canceled, local officials told Radio France Internationale.
Haute-Marne was one of several areas of France battered by powerful storms overnight, RFI said.
Other injuries a woman hurt by a falling steeple and a mail carrier who was hit by lightning.
Rail transportation was getting back to normal Sunday but more than 130,000 homes were without power. Storm warnings remained in effect in central and southeastern France.