A stabbing Monday at a children's dance class in northwest England killed two children and wounded 11 other people, police said, and officers arrested a 17-year-old boy and seized a knife after the bloody rampage.
Nine children and two adults were wounded in the attack in Southport, a seaside town near Liverpool, Merseyside Police said. Six children and both adults were in critical condition.
Police Chief Constable Serena Kennedy said the wounded adults had "bravely" tried to protect the children during the "ferocious" attack.
"The offender, who was armed with a knife, walked into the premises and started to attack those inside," Kennedy said. "We believe that the adults who were injured were trying to protect the children at the time they were attacked."
A witness described seeing bloodied children running from the class that was held for children aged about 6 to 11 on the first day of summer school vacation. An advertisement for the event promised "a morning of Taylor Swift-themed yoga, dance and bracelet making."
Kennedy said the motive for the attack is unclear. Police said earlier that detectives were not treating the attack as terror-related.
Bare Varathan, who owns a shop nearby, said he saw at least seven kids injured and bleeding outside a nursery.
"They were in the road, running from the nursery," Varathan said. "They had been stabbed, here, here, here, everywhere," he said, indicating neck, back and chest.
Prime Minister Keir Starmer called the attack "horrendous and deeply shocking."
Merseyside Police said officers were called at about noon to an address in Southport, a seaside town of about 100,000 people near Liverpool. Police called it a "major incident" but said there was no wider threat to the public.
The suspect, who has not been identified, lived in a village about 5 miles (8 kilometers) from the site of the attack, police said.
Ryan Carney, who lives with his mother in the area, said his mother saw emergency workers carrying children "covered in red, covered in blood. She said she could see the stab wounds in the backs of the children."
"All this stuff never really happens around here," he said. "You hear of it, stabbings and stuff like that in major cities, your Manchesters, your Londons. This is sunny Southport. That's what people call it. The sun's out. It's a lovely place to be."
Britain's worst attack on children occurred in 1996, when 43-year-old Thomas Hamilton shot 16 kindergarten pupils and their teacher dead in a school gymnasium in Dunblane, Scotland. The U.K. subsequently banned the private ownership of almost all handguns.
Mass shootings and murders with firearms are rare in Britain, where knives were used in about 40% of homicides in the year to March 2023. Several headline-grabbing attacks and a recent rise in knife crime have stoked anxieties and led to calls for the government to do more to clamp down on bladed weapons.