More than three dozen people, many of them children, were injured on Saturday, when lightning struck different playgrounds in France and Germany. Both occurrences were unrelated.
Eleven people, most of them children, were injured at a birthday party in a Paris park, officials said. Six of the victims were seriously injured.
Eight children and three adults were hurt when the storm hit as they were holding celebrations in Parc Monceau in northwest Paris, police said.
"They had taken shelter under a tree," said Paris official Karen Taieb.
Three of the children and one adult had life-threatening injuries, the Paris force said, with another child and another adult also seriously injured.
The children were aged between 7 and 14.
Local official Vincent Baladi, speaking to iTELE television, had earlier given a slightly different toll of 10 children and one adult injured.
"We hope they will all pull through," said Baladi, who handles security matters in Paris' eighth arrondissement where the park is located.
"They have burns," he said, adding that paramedics and firefighters were at the scene. "The lightning struck suddenly."
The injured were taken to Necker hospital, a specialist children's hospital in southwest Paris.
The park, in a well-heeled neighbourhood of the city's northwest, and is popular with families on the weekend.
In the other incident, lightning struck a football pitch in western Germany, injuring 35 people, three of them seriously.
The accident occurred at the end of a children's football match in Hoppstaedten.
The referee of the children's match was struck directly by the lightning. He was immediately taken to hospital.