Cardiff born teenager held by police after fatal Southport attack
Two adults, who tried to stop the attacker, are also critical
Six children remain in a critical condition in hospital this morning after a knife attack in Southport, with two children having died.
Two adults, who it's thought tried to stop the attacker, are also critical.
The attack took place at a Taylor Swift-themed holiday dance class on Hart Street on Monday morning.
All the casualties are now being treated in hospitals, including at Alder Hey and the Royal Manchester Children’s hospitals.
A 17-year-old boy, born in Cardiff, is being held on suspicion of murder and attempted murder following the attack, and a property in nearby Banks is being searched by specialist officers.
The King said on Monday evening that he and the Queen had been "profoundly shocked" to hear of the "utterly horrific incident in Southport today".
Charles added: "We send our most heartfelt condolences, prayers and deepest sympathies to the families and loved ones of those who have so tragically lost their lives, and to all those affected by this truly appalling attack."
The Prince and Princess of Wales said: "As parents, we cannot begin to imagine what the families, friends and loved ones of those killed and injured in Southport today are going through.
"We send our love, thoughts and prayers to all those involved in this horrid and heinous attack.
"Thank you also to the emergency responders who, despite being met with the most horrific scenes, demonstrated compassion and professionalism when your community needed you most."
One local said one of the two adults injured in the attack locked herself in a room with children to protect them as eyewitnesses reported hearing screaming and seeing children "covered" in blood, suffering stab wounds.
MP for Southport Patrick Hurley posted a statement on X: "My thoughts and prayers go out to the victims and families of the horrific attack on Hart Street today.
"I am deeply saddened by the news that two children have been fatally injured.
"I hope for the swift and full recovery of all the other victims of this senseless attack and I thank the staff at Alder Hey Children's Hospital, Southport and Formby Hospital, and Aintree University Hospital for their care for those affected."