Two children are dead and six in a critical condition after a suspected teenage knifeman attacked a Taylor Swift-themed holiday dance class.

The 17-year-old suspect, born in Cardiff, is being held on suspicion of murder and attempted murder after the incident in Hart Street, Southport, Merseyside, police said.

The ages of the dead children, or whether boys or girls, have not been given by police, who said they are not treating the incident as terror-related but the motive “remains unclear”.

Three other children were injured and two adults also left in a critical condition, injured trying to protect the youngsters, police said.

The suspect is from Banks, a village outside Southport, with police now stationed outside an address.

Merseyside Police had declared a major incident at the scene in Southport, after receiving emergency calls at 11.50am on Monday, with armed response vehicles, 13 ambulances and the fire service descending on the mass casualty scene, a school holiday club for children aged six to 11.

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.

Merseyside Police Chief Constable Serena Kennedy, giving a statement to media in Southport on Monday evening, said officers were called to a “ferocious” attack.

She said: “When they arrived, they were shocked to find that multiple people, many of whom were children, had been subjected to a ferocious attack and had suffered serious injuries.

“It is understood the children were attending a Taylor Swift event at a dance school when the offender armed with a knife walked into the premises and started to attack the children inside.

“As a mum of two daughters, and the nanna of a five-year-old grand-daughter, I cannot begin to imagine the pain and suffering the families of the victims are currently going through, and I want to send them our heartfelt condolences and sympathies.”

Police did not take questions from the press about the incident.

All the casualties are now being treated in hospitals, including children’s hospitals in Liverpool and Manchester.

Emergency services described a “horrific” and “chaotic” scene as they arrived at the children’s club.

Colin Parry, owner of Masters Vehicle Body Repairs, near the scene, said: “It is like a scene from a horror movie. It’s like something from America, not like sunny Southport.”

A large police cordon has been put up around the building in Hart Road, with police officers guarding either end.

Bare Varathan, 35, who owns a corner shop in Hart Street, said: “I saw seven to 10 kids outside the nursery. They had been stabbed, here, here, here, everywhere. (Mr Varathan indicated the neck, back and chest area)

“They were all aged about 10.”

One resident, who lives in Hart Street but did not want to be named, said he was at home about midday when a woman pulled up outside in her car, screaming.

He said: “She was screaming ‘my daughter’s been stabbed’.

“The woman was in hysterics. Then two police cars rushed up the street the other way.

“It was a mum with her 10-year-old daughter who had been stabbed.

“I helped to get her back up to where the police cars and ambulances were.

“She didn’t look great but my focus was on getting her back up the street to get help.

“When I got back up the street there were a couple of kids on the floor being seen to by paramedics and, as I came back, more police cars were going down and more ambulances gradually started to arrive.”

Prime Minister Keir Starmer said: “The events today are just truly awful and I know the whole country is deeply shocked at what they have seen and what they have heard.

“I know I speak for everybody in the whole country in saying our thoughts and condolences are with the victims, their families, their friends and with the wider community.

“It is impossible to imagine what they are going through right now.”

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.”