Southport, UK - Taylor Swift said she was "completely in shock" on Tuesday after mass stabbings in Southport, northern England, during a dance class themed around the pop star left three girls dead.

Five young children and two adults remained in critical condition, with police confirming three girls aged six, seven, and nine were killed in a stabbing spree at an events space in the seaside town near Liverpool.

The third girl, aged nine, died on Tuesday due to her injuries, while the other two died on Monday.

"The horror of yesterday's attack in Southport is washing over me continuously, and I'm just completely in shock," Swift wrote in an Instagram post about the incident, which also left eight others critically injured.

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

Swift fans also raised over $77,000 for the families of victims through a fundraiser on JustGiving.

Held at the start of the UK school holidays for children aged between 6 and 11, the event was a dance and yoga class with a bracelet-making activity. The organizer had posted on Facebook, "Calling all Swifties!" to sign up for the workshop.

A fundraiser called "Swifties for Southport" was raising money for the families affected, which would go to Alder Hey Children's Hospital, where some of the victims were taken by ambulance after the attack.

The fundraiser, made by the organizers of the Taylor Swift UK & EU Facebook group, had raised £39,375 to support families and pay for the funerals of the two children who were killed.

"Every donation through this link goes directly to the verified charity" and will "help make a difference to those impacted in a time of great sadness," the organizers wrote on the fundraiser page.

A 17-year-old male was arrested on suspicion of murder and attempted murder. While the motivation of the attack was not clear, police confirmed it was not being treated as terror-related.