Police revealed a third child, a nine-year-old girl, died on Tuesday. Two girls aged six and seven previously died following Monday’s attack in Southport.

Five children and two adults are in critical condition in hospitals.

Police were questioning a suspect and working on to understand what motivated a 17-year-old boy to attack the children at the start of the UK’s summer school holidays.

Swift said she was “completely in shock” and still taking in “the horror” of the event.

“These were just little kids at a dance class,” she wrote on Instagram on Tuesday.

“I am at a complete loss for how to ever convey my sympathies to these families.”

A total of nine children and two adults were hurt in the rampage in Southport, north of Liverpool. Both adults and children were rushed to local hospitals in a “major incident”.

A 17-year-old boy was arrested on suspicion of attempted murder and was being questioned by police over the attack.

Local people left flowers and stuffed animals in tribute at a police cordon on the street lined with brick houses in the seaside resort nicknamed “sunny Southport”, whose beach and pier attract vacationers from across north-west 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 five kilometres 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.

“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.

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 6 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”. King Charles III 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 that 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.