A third child has died after a knife attack in Southport, England, and five children and two adults remain in a critical condition, the police said on Tuesday.

A 9-year-old girl died in the hospital in the early hours of Tuesday, the police said in a statement, while two other girls, age 6 and 7, died on Monday as a result of their injuries.

The attack, which the local police chief, Serena Kennedy, described as “ferocious,” took place at a Taylor Swift-themed dance class for children age 6 to 11. A 17-year-old boy was arrested and is being questioned by the police.

Ms. Swift said in a statement about the attack on Instagram that she was “completely in shock.”

“The horror of yesterday’s attack in Southport is washing over me continuously,” she wrote, adding: “The loss of life and innocence, and the horrendous trauma inflicted on everyone who was there, the families, and first responders. These were just little kids at a dance class.”

Prime Minister Keir Starmer is expected to visit the scene on Tuesday, Rachel Reeves, the chancellor of the Exchequer, told Sky News.

Here’s what we know.

How did the attack unfold?

A group of children were attending a Taylor Swift-themed yoga and dance workshop at a studio in Southport on Monday when the attack took place.