Three young girls have been killed in a "ferocious" knife attack in Southport at a Taylor Swift-themed dance and yoga event.
They have been named as six-year-old Bebe King, Elsie Dot Stancombe, aged seven, and nine-year-old Alice Dasilva Aguiar.
Eight more children were injured, with five left in a critical condition, after the incident late on Monday morning. Two adults also suffered critical injuries, Merseyside Police said.
Armed officers detained a male and seized a knife, with police later saying that a 17-year-old boy had been arrested on suspicion of murder and attempted murder. The attack is not being treated as terror-related, police said.
Here is what we know so far about the attack.
How did the attack unfold?
Police were called to reports of a stabbing at a property on Hart Street in Southport just before 11:50 BST on Monday.
Officers were "shocked" to find multiple people, many of whom were children, had been subjected to a "ferocious attack" and had suffered serious injuries.
Police believe a group of children were attending an event at a dance school when a person armed with a knife walked into the building and attacked those inside.
Two adults were critically injured "bravely" trying to protect the children from the attack, police said.
Six-year-old Bebe King and seven-year-old Elsie Dot Stancombe died on Monday, while Alice Dasilva Aguiar, aged nine, died in hospital early on Tuesday morning from injuries sustained in the attack.
In a tribute issued through police, Bebe's family said: "No words can describe the devastation that has hit our family as we try to deal with the loss of our little girl Bebe."
Meanwhile, the family of Alice said: "Keep smiling and dancing like you love to do our Princess, like we said before to you, you're always our princess and no one would change that. Love from Your Hero Daddy and Mummy."
Her parents are from Madeira in Portugal but the family now lives in Southport, a Portuguese government minister said.
As well as the three children who were killed, eight more suffered stab wounds in the attack and five were left in a critical condition.
North West Ambulance Service (NWAS) said it had treated 11 casualties with stab injuries.
Alder Hey Children's Hospital in Liverpool confirmed on Tuesday that a child had died at the hospital after the "heartbreaking incident in Southport".
Six other children continue to receive treatment with two remaining in critical care but currently in a stable condition, the hospital added.
Air ambulance doctors delivered "advanced emergency care" for one patient and accompanied them to hospital by road, the Great North Air Ambulance service.
Where did the attack happen?
The incident happened at a Taylor Swift-themed yoga and dance event in the Merseyside town of Southport, about 10 miles north of Liverpool.
The event was taking place at the Hart Space studio, close to a vehicle repair garage, in Hart Street, roughly a mile east of the centre of town.
The holiday club was advertised as including a dance and yoga workshop as well as bracelet making, and was aimed at primary school children in Year 2-Year 6.
It is thought to have been fully booked with 25 children attending.
The BBC understands Leanne Lucas, thought to be 35, was running the holiday club. Her condition is not known, however tributes have poured in on social media, praising her bravery.
At the scene, flowers and teddies had been left by the police cordon, with one message saying: "Fly high with angels little ones."
Hundreds of people attended a vigil on Tuesday evening outside the Atkinson cultural centre, just a mile away from Southport's iconic pleasure beach.
People laid flowers and lit candles, and a minute's silence was held. Jane Burns, the mayor of Sefton, told the crowd: "I hope all of you here find some comfort from something, even if it's someone you meet here today, a stranger."
A JustGiving page called Swifties for Southport, set up by fans of the singer to raise money for Alder Hey Children's Charity, had more than £270,000 in donations as of 09:00 BST on Wednesday.
What do we know about the suspect?
Merseyside Police confirmed that armed police "detained a male and seized a knife" following the incident, and said there was no wider threat to the public.
The force later said a 17-year-old boy from Banks, a Lancashire village to the north of Southport, was arrested on suspicion of murder in connection with the stabbing. He was originally from Cardiff, they added.
He remains in custody and is being questioned about the incident, as police work to establish the motive for the attack.
Detectives were granted more time to question him on Wednesday.
One witness said the person they believed to be the attacker arrived in a taxi wearing a face mask and refused to pay the fare.
The BBC understands the teenager, who cannot be named for legal reasons, moved to the Southport area in 2013. His parents are from Rwanda and he has an older brother also born in Cardiff.
Helen, a neighbour of the family while they lived in Cardiff, has spoken of her shock, and said the family had come from Rwanda.
She told the BBC: "They were a lovely young couple. They were little boys, they were boisterous. Mum was a stay at home mum, Dad was nice, he went to work every day. They had a small family car, a little hatchback."
Detectives from Counter Terrorism Policing North West are actively providing support to the investigation, the BBC understands, although police said the incident is not currently being treated as terror-related.
They said a name shared on social media in connection with the suspect is "incorrect", adding: "We would urge people not to speculate on details of the incident while the investigation is ongoing."
What have witnesses said?
Eyewitnesses spoke of horrific scenes in the aftermath of the attack, with one describing it as the "worst thing I’ve seen in my life".
Multiple people reported seeing several young children bleeding in the road after being stabbed.
Speaking to Sky News, window cleaner Joel Verite said he heard a woman screaming "he's stabbing kids" as he drove near the dance studio.
Mr Verite said he saw a woman in a car with a child in the passenger seat, with "four or five more kids, covered in blood" in the back.
"It was like a scene you'd see on a disaster film, honestly. I can't even explain how horrific it was," he added.
Mr Verite said he carried a girl out of the car to get her to safety before returning to the studio.
Joel Verite described locking eyes with a man holding a knife inside the studio building before the alleged attacker "scurried off".
Asked what was going through his head, he said: "I'm really scared, all I saw was a knife... I'm there by myself at the bottom of the stairs."
The knifeman was later "tackled down to the floor" by police, he added.
Tim Johnson, a journalist with Eye on Southport, saw one girl on a stretcher who was seriously injured, and said paramedics were among "people in tears in the streets".
Several witnesses say they heard a woman running down the road screaming "my daughter's been stabbed".
Another witness said they took around 10 girls to safety in a nearby house.
Taylor Swift and leaders react
Taylor Swift posted on her Instagram story on Tuesday, saying the horror of the attack was "washing over me continuously", and that she was "completely in shock".
"These were just little kids at a dance class," she added. "I am at a complete loss for how to ever convey my sympathies to these families."
Home Secretary Yvette Cooper visited Southport on Tuesday morning and laid flowers near the scene.
Prime Minister Sir Keir Starmer also travelled to the area later in the day, saying the attack "touches a nerve" with the whole country and it was "awful to contemplate what happened".
King Charles III said on Monday night that he and the Queen were "profoundly shocked".
In a statement posted on X, the King said they sent their "heartfelt condolences, prayers and deepest sympathies" to everyone affected by the "appalling attack".
The Prince and Princess of Wales also sent "love, thoughts and prayers" to the victims of the "heinous" attack, saying: "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."
Unrest 'hijacks grief' of families
Violent protests broke out in Southport hours after the vigil was held.
At about 19:45 BST on Tuesday, demonstrators gathered and engaged in a stand-off with police officers.
Officers were pelted with bricks and a police van was set on fire, Merseyside Police said.
The force said eight of its officers sustained serious injuries.
In total, 27 officers were taken to hospital, and 12 were treated and discharged at the scene, the ambulance service said.
Police said the violence was believed to have involved English Defence League supporters.
The town's MP, Patrick Hurley, described the violence - close to a mosque - as "horrific", saying those involved had “hijacked the grief” of families.
On Wednesday morning, dozens of local residents with brushes and shovels helped with the clean-up operation after the protests.
Normal Wallis, chief executive of Southport Pleasureland, praised the "fantastic" response from the community.
He added: "It's horrendous what those hooligans have done last night. It was like a war scene. People from out of town just causing absolute mayhem."
Merseyside Police
Southport