LONDON — Taylor Swift said Tuesday that she was “completely in shock” after three children were killed at a dance workshop celebrating her music in a small British seaside town.

Eight other children were injured, five of them critically, in what police called a “ferocious” knife attack Monday in Southport, a seaside town in northwest England near Liverpool. On Tuesday, authorities announced the third child had died.

Two adults were also critically injured as they tried to defend the children, Merseyside Police said.

“The horror of yesterday’s attack in Southport is washing over me continuously and I’m just completely in shock,” Swift said in an Instagram Live post.

“These were just little kids at a dance class,” she added. “I am at a complete loss for how to ever convey my sympathies to these families.”

Her comments came as local people left flowers and stuffed animals in tribute at a police cordon near where the incident took place in the town, which is famed for its beach and pier. British Home Secretary Yvette Cooper was among those to visit the memorial.

Police said a 17-year-old boy was arrested in connection with the attack. Investigators said he was from the nearby village of Banks, but did not offer a motive. However, they said the attack was not being treated as terror-related and that no one else was believed to be connected.

Under the United Kingdom’s law, the identity of a child aged between 10 and 17 charged with a crime will not be disclosed outside the court.

Shortly after the incident, Colin Parry, who owns the business next to the community center that was hosting the children’s event, told the British broadcaster Sky News that one of his colleagues called him and told him to get outside, where he witnessed utter horror.

“It was definitely intentional. It wasn’t once. It was several times he stabbed these kids,” he said. (Sky News is owned by Comcast, the parent company of NBC News.)

King Charles III was among those to also express horror at the attack, with the monarch saying Monday that both he and Queen Camilla were “profoundly shocked to hear of the utterly horrific incident in Southport” and offered their “most heartfelt condolences” to the families impacted.

A Just Giving online fundraiser called “Swifties for Southport” had raised more than £100,000, or around $128,500, as of Tuesday for the families grieving after the attack.

The U.K.’s worst attack on children occurred in 1996, when a 43-year-old man fatally shot 16 kindergarteners and their teacher in a school gymnasium in Dunblane, Scotland. The U.K. 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% of homicides in the year to March 2023.