In total, three girls have died and eight others are still being treated for their injuries. For five of them, their condition is deemed critical, according to the police and authorities.
The three victims, named by the British police, were six, seven, and nine years old.
The children were at a Taylor Swift-themed event on Monday when the perpetrator attacked. Witnesses describe the scene as "taken from a horror movie" and as "the worst they've seen".
Two adults were also injured in the attack, and their condition is also described as critical.
But after a day of mourning, memorial services, and official visits, Southport, in northwestern England, north of Liverpool, turned into a place for unexpected clashes.
A group of people gathered outside a mosque in Southport immediately after a manifestation for the victims was held, and suddenly riots broke out when the group began throwing bricks at the mosque and at the police, reports BBC.
A police car was set on fire, and riot police were deployed against the violent crowd. According to media reports, individuals from right-wing extremist groups were among the rioters.
Merseyside's Deputy Chief Constable Alex Goss called the development "abhorrent".
Our police and rescue services were faced yesterday with one of the toughest tasks they will ever have to deal with. Tonight, they are being attacked as they try to quell unrest, said Goss on Tuesday evening.
The unexpected turn of events in the tragedy-stricken town came after, among others, Prime Minister Keir Starmer visited Southport.
Thanks rescue services
Starmer visited the crime scene on Tuesday afternoon to express his condolences and show his support for the families of the victims.
He also chose to personally thank the police and rescue services who were quickly on the scene.
I believe that everyone in this country is affected by what has happened, said Starmer.
But Starmer was also met with criticism when he laid flowers at a memorial site. "How many more have to die on our streets?" shouted a man in a group of hecklers who expressed their discontent with the Prime Minister.
A 17-year-old has been arrested and detained for the deed and was questioned by the police on Tuesday. Any motives were still unknown.
