Video footage shows the dramatic moment a house was raided in Southport by armed police following a horrific mass stabbing.

It follows the death of two children in a knife attack in Southport on Monday, which left nine other children injured. Merseyside Police confirmed a 17-year-old boy has been arrested.

The teenager, from the village of Banks, and originally from Cardiff, is currently being questioned on suspicion of murder and attempted murder. Police were called to an address in Hart Street behind which is The Hart Space studios, where children were taking part in a Taylor Swift-inspired dance class.

ITV UK Editor Paul Brand wrote on Twitter: "The scene of the attacks is around a 15-minute drive from this location.

"Armed police arrived around two hours later to raid the house."

READ MORE: Southport stabbing latest updates: Two children dead and nine injured in rampage

Police confirmed everyone's worst fears ealier this evening when they revealed two children tragically lost their lives and six others were battling for survival following the horrific stabbing incident at the Taylor Swift themed dance workshop at the children's centre.

In a harrowing press conference, police revealed that two brave adults who attempted to intervene when a suspect entered with a knife and began attacking the children were left with severe injuries and are both in critical condition. Harrowing details from the scene describe a mother screaming "my daughter's been stabbed."

A local resident described hearing a woman's screams and rushing outside to find a young mother and her approximately 10-year-old daughter, both covered in blood. Deborah Parker, 57, who resides a few hundred yards from the centre, discovered the pair in a car near her home.

She recounted: "It had only just happened. I was opening the windows downstairs and a police car sped past. The lady was parked on the corner screaming 'help me, help me'. Of course I ran over, she was covered in blood, the mum. Her daughter was slumped in the passenger seat.

"She had gone to the children's club to pick her up and she came out saying 'mum, I've been stabbed'. Her mother had bundled her in the car and just sped away because she did not know what was happening. She stopped here, I was saying 'how has this happened' and she didn't know because her daughter couldn't speak. All she could say was she had been stabbed."

Detectives released an update on inquiries into motive for the horrific attacks this afternoon and gave further details on who was arrested. Officers say the stabbings aren't currently being treated as terror-related and that the suspect is a 17-year-old who was born in Cardiff but now lives in Banks, Lancashire. Police were seen searching a house in Banks shortly before his arrest was made public.

Merseyside Police Chief Constable Serena Kennedy said as well as the two children who died, nine children were injured in the “ferocious” attack and two adults are also in a critical condition.

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, William and Kate, 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.”

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”.

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