Charges for the murder of the three girls in Southport, Britain, and 10 more attempted murders have been brought against a 17-year-old who is already in custodyBritish police announced.

Bebe King, six, Elsie Dot Stancombe, seven, and nine-year-old Alice Dasilva Aguiar died after being stabbed at a Taylor Swift-themed event in the Merseyside city on Monday.

Against the teenager, who is to be presented at City of Liverpool Magistrates’ Court later Thursday, 10 counts of attempted murder have also been filed.

Eight other children and two adults who attended the event at the Hart space center were injured, some of them in critical condition.

The accused, who has not been named due to his age, has also been charged with possession of the knife.

Ursula Doyle, deputy chief prosecutor for Mersey-Cheshire Crown Prosecution Service, said: “We would like to remind all concerned that criminal proceedings against the accused are active and that he is entitled to a fair trial.

“It is extremely important that there is no reporting, commenting or sharing of information online that could in any way harm these processes.

“Our thoughts remain with the families of all those affected by these painful events.”

Merseyside’s Chief Constable Serena Kennedy said: “While these charges are a significant milestone in this investigation, it remains very much active and we continue to work with our partners from Lancashire Constabulary and counter-terrorism police.”

Primary school children aged six to 10 took part in the summer holiday dance class in Southport’s Hart Street. Two adults were seriously injured “bravely” trying to protect the children from the attack, police said.

In protests over the incident, more than 100 people were arrested in central London on Wednesday night, the Metropolitan Police said.

The Met said it had made arrests for a range of offences, including violent disorder, assaulting an emergency worker and breaching protest conditions on Wednesday afternoon.

Riots also took place on Tuesday in Southport.

A large group of protesters stormed the front of a mosque, hurling bricks, bottles, fireworks and stones, while police used shields to defend themselves as protesters threw objects at them. A police vehicle was also set on fire.

Merseyside Police said more than 50 officers were injured in a “prolonged and savage attack”. Authorities said the violent incidents were believed to have involved supporters of the English Defense League.

He added that the protesters had been incited by social media posts suggesting the attack was Islamist-motivated.