A stabbing Monday at a children’s dance class in northwest England killed two children and wounded 11 other people, police said, after which officers arrested a 17-year-old boy and seized a knife.

Nine children and two adults were wounded in the attack in Southport, a seaside town near Liverpool, Merseyside police said. Both adults and six of the children 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.”

A witness described seeing bloodied children running from the class that was held for children aged about six 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 down the street, 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 the neck, back and chest. 

‘Horrendous and deeply shocking’

British Prime Minister Keir Starmer called the attack “horrendous and deeply shocking.”

Merseyside police said officers were called around noon to an address in Southport, a town of about 100,000 people. It called it a “major incident” but said there was no wider threat to the public. It asked people to avoid the area.

Colin Parry, who owns an auto repair shop near the site of the attack, said the attack was “like something from America, not like sunny Southport.”