PARIS (AP) — As bystanders screamed for help, a man with a knife stabbed several very young children, including at least one in a stroller, and also assaulted adults in a lakeside park in the French Alps on Thursday. The savagery left at least two children and one adult with life-threatening injuries, authorities said.

A suspect, identified by police as a 31-year-old Syrian asylum-seeker, was detained.

Video appearing to show the attack in a children's play park in the Alpine and lakeside town of Annecy was posted on social media. The horrific scenes showed a man in dark glasses and with a blue scarf covering his head brandishing a knife, as people screamed for help.

He first circled the playground, slashing at a bystander, and then clambered over its barriers to attack people and children inside. He appeared to stab one child in a stroller repeatedly.

French President Emmanuel Macron described the assault as an “attack of absolute cowardice.” Of the victims, he said “children and an adult are between life and death.”

“The nation is in shock,” Macron tweeted.

Local police said the four child victims were all under age 5.

National police said two of the children, both around 3, suffered life-threatening injuries, as did one adult.

A witness who spoke to French broadcaster BFMTV said he saw the attacker jumping on an elderly man, and stabbing him repeatedly. The witness said he yelled at police to act.

“I screamed, screamed at them to intervene,” he said.

An ice cream seller who works in the waterside park said he'd seen the attacker there several days earlier, looking out at the lake ringed by mountains.

Local police said a second adult also was injured and was being treated with the others in a hospital. They gave no other details about the victim, and the discrepancy in the number of adult victims wasn't immediately explained.

A local lawmaker, Antoine Armand, said the children were attacked on a playground in the park. Speaking to BFMTV from the National Assembly building in Paris, he said the victims included “very young” children and that they were “savagely attacked.” The attack took place close to a primary school, he said.

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.”