Three children are in a life-threatening condition after a knife attack in Annecy in southeast France, police have said.
Four children and an adult were injured in total, officers added.
The youngsters are all about three years of age, police said.
Interior Minister Gerald Darmanin said a suspect had been arrested “thanks to the swift intervention of police”.
Local politician Antoine Armand tweeted that children were attacked in a playground, describing the attack as “abominable”.
The assailant was a Syrian asylum seeker, BFM TV reported.
In Paris, politicians interrupted a debate to hold a moment of silence for the victims, BFMTV said.
Francois Astorg, the mayor of Annecy, said he was at the scene and will be speaking at lunchtime.
He urged people to avoid the Paquier area of the town and said his thoughts were with the victims and their families.