The day after the attack, a mountain of flowers and teddy bears begins to grow outside the police cordons.
"Sleep tight, beautiful angels. You are all fantastic! We regret the sorrow", reads a card on a bouquet of flowers.
Several witnesses describe the scene that unfolded the day before as "like something out of a horror movie". One of them is Colin Parry, who runs a car workshop just next to the venue where the children had gathered for an event in the spirit of Taylor Swift.
One of Parry's employees had gone out from the workshop because he had heard children's screams that didn't sound like "ordinary children's screams", he tells BBC.
"Why?"
We rushed out and there were small children, all bleeding, says Parry.
Why? Why would anyone want to do something like that to children? It's horrific.
A woman who lives in the area testifies that she saw bodies covered in blood and that she could see the stab wounds, reports Sky News.
Two children died from their injuries on Monday evening, and on Tuesday, the police announced that another child had died after the attack.
17-year-old arrested
The blue light response in Southport was massive after the deed, and the police confirmed on Monday that a 17-year-old, armed with a knife, had been arrested and detained.
The attack has received widespread attention. King Charles and Queen Camilla express great sorrow, and Britain's Prime Minister Keir Starmer says that the whole country is "deeply shocked".
Southport, with around 100,000 inhabitants, is located on the coast a few miles north of Liverpool.
The site of the attack is described as a quiet residential area.
