Four very young children have been stabbed in a park near Lake Annecy, in France’s south-east, the interior minister says.
Police overpowered and arrested the attacker, Gérald Darmanin said.
Reports say the children were aged about three years old and at least two were in a critical condition.
Regional deputy Antoine Armand described the attack as “abominable” and French prime minister, Élisabeth Borne, is on her way to the scene.
Mr Armand said authorities were investigating and knew “very little”, but his thoughts were with the victims and their loved ones.
Local officials earlier said six children were injured in the attack, but authorities later confirmed there were six victims in total, including four children.
The suspect is believed to be a Syrian refugee, according to reports from Le Parisien, BFM TV and AFP quoting police sources.
He attacked the children – some in pushchairs – as they visited the park, before fleeing the scene and stabbing an elderly man nearby.
Police intervened and the perpetrator was shot in the legs.
France’s National Assembly has observed a minute of silence and roads are blocked around the scene of the attack.
President Emmanuel Macron tweeted that the nation was in “shock” over the “act of cowardice”.