A total of nine children and two adults were hurt in the rampage in Southport, northwest England. Both adults and six of the children were in critical condition in local hospitals.
"We believe the adults who were injured were bravely trying to protect the children who were being attacked," Merseyside Police Chief Constable Serena Kennedy said.
Witnesses described 'horror movie' scenes as children covered in blood ran from the knife attack. (AP PHOTO)
Locals left flowers and stuffed animals in tribute at a police cordon on the street lined with brick houses in the seaside resort near Liverpool - nicknamed "sunny Southport" - where the beach and pier attract holidaymakers from across northwest England.
Witnesses described scenes "from a horror movie" as bloodied children ran from the attack just before noon on Monday.
The suspect was arrested soon after on suspicion of murder and attempted murder.
Police said he was born in Cardiff, Wales, and had lived for years in a village about 5km from Southport. He has not yet been charged.
Police said detectives are not treating Monday's attack as terror-related and they are not looking for any other suspects.
Police are interviewing a 17-year-old boy from Wales who was arrested soon after the incident. (AP PHOTO)
It is the latest shocking attack in a country where a recent rise in knife crime has stoked anxieties and led to calls for the government to do more to clamp down on bladed weapons.
Witnesses described hearing screams and seeing children covered in blood emerging from the Hart Space, a community centre that hosts everything from pregnancy workshops and meditation sessions to women's boot camps.
The attack happened during a Taylor Swift-themed yoga and dance workshop for children aged about six to 11.
"They were in the road, running from the nursery," said Bare Varathan, who owns a shop nearby. "They had been stabbed, here, here, here, everywhere," he said, indicating the neck, back and chest.
Prime Minister Keir Starmer called the attack "horrendous and deeply shocking".
A message from His Majesty The King following the tragic incident in Southport today. — The Royal Family (@RoyalFamily) pic.twitter.com/4aUK8btptXJuly 29, 2024
King Charles sent his "condolences, prayers and deepest sympathies" to those affected by the "utterly horrific incident".
Prince William and his wife Catherine said that "as parents, we cannot begin to imagine what the families, friends and loved ones of those killed and injured in Southport today are going through".
Colin Parry, who owns a nearby auto body shop, told The Guardian the suspect arrived by taxi.
"He came down our driveway in a taxi and didn't pay for the taxi, so I confronted him at that point," Parry was quoted as saying. "He was quite aggressive, he said, 'What are you gonna do about it?'"
Parry said most of the victims appeared to be young girls.
"The mothers are coming here now and screaming," Parry said. "It is like a scene from a horror movie ... It's like something from America, not like sunny Southport."
Britain's worst attack on children occurred in 1996, when 43-year-old Thomas Hamilton shot 16 kindergarteners and their teacher dead in a school gymnasium in Dunblane, Scotland.
The UK subsequently banned the private ownership of almost all handguns.
Mass shootings and killings with firearms are rare in Britain, where knives were used in about 40 per cent of homicides in the year to March 2023.
