A seven-year-old boy and his elder sister have been killed during a fireworks display to mark France’s national day in the western town of Cholet.
“A rocket exploded in the middle of people,” said Mayor Gilles Bourdouleix.
He described how the victims were with other family members 50m (160ft) from where the fireworks were being let off.
The explosion sent spectators fleeing in panic and left areas of grass in flames.
The boy was killed instantly and his 24-year-old sister died later of a heart attack, according to French reports. Seven others were hurt. Their parents suffered from shock, while a man described as close to the sister sustained serious burns.
Local prosecutors have opened an investigation for manslaughter.
Cholet was holding its first Bastille Day fireworks display for three years because of the Covid pandemic. The explosion happened shortly after 23:00 on Thursday night on a football pitch a short distance from firework launchpad.
“It started off as a really pretty firework display. Then suddenly a rocket careered towards us… and exploded in the crowd, causing a lot of damage,” one witness, Manon, told BFMTV. “Everyone got up and screamed and started to put out the flames with our feet or whatever we had in our hands”.
The first indication of what had gone wrong came from public prosecutor Éric Bouillard, who told Le Parisien that according to initial investigations one of the blocks of fireworks had malfunctioned. That had prompted one of the crates to explode, setting off some of the rockets instantly.
Most spectators had been watching further away in the main square but others had been looking on from the football pitch, behind fencing around the town stadium.
The mayor said an orchestra had been playing from a podium and the organisers had not expected people to watch from the football field, adding that the company involved had been doing it for years and had a good reputation.
Cholet had been enjoying a party and the people had been dancing, he said, “and it ends up in this horribly dramatic way”.