Four toddlers and two adults were stabbed in a knife attack in the tranquil French mountain town of Annecy on Thursday, and the government said the suspected assailant was a Syrian refugee.
Two of the children and one adult were in hospital in a life-threatening condition, while the other victims were less seriously hurt.
A video of the attack, taken by a bystander and verified by Reuters, showed the assailant jump a low wall into a children's playground and repeatedly lunge at a child in a stroller, pushing aside a woman who tries to fend him off.
Prime Minister Elisabeth Borne said the suspected attacker, who was in police custody, was a 31-year old Syrian national who was granted asylum in Sweden 10 years ago. He had entered France legally, she said, and was carrying Swedish identity documents and a Swedish driving license.
The four children were just toddlers, aged between 22 months and three years, Annecy prosecutor Line Bonnet-Mathis told reporters.
One of them was a British national, another was Dutch, Bonnet-Mathis said.
As the assailant, who wore a blue-chequered headscarf and sunglasses, slashed at his victims, one bystander tried to stop him by throwing his backpack at him, the video showed.
The incident took place at around 0745 GMT in Le Paquier park in Annecy, a town in the French Alps.
"The nation is in shock," President Emmanuel Macron said on Twitter, calling the attack "an act of absolute cowardice.”
In Paris, lawmakers interrupted a debate to hold a moment of silence for the victims.
The assembly president, Yaël Braun-Pivet, said: "There are some very young children who are in critical condition, and I invite you to respect a minute of silence for them, for their families, and so that, we hope, the consequences of this very grave attack do not lead to the nation grieving.”