Rob Smith reporting from the scene of the fatal stabbing of 12-year-old Ava White in Liverpool.
A 12-year-old girl has died following an assault in Liverpool city centre.
It is thought Ava White was with friends on Church Alley when Merseyside Police say a "verbal argument" broke out with a group of boys.
An assault is believed to have taken place, where Ava "collapsed to the ground", and officers say "a member of the public who witnessed the incident was giving first aid".
It is understood the offenders were seen to "run up School Lane across Hanover Street and on to Fleet Street".
Police and paramedics attended the scene, shortly after 8.39pm and Ava was taken to Alder Hey Children’s Hospital, where she died a short time later.
Four teenage boys – one aged 13, two aged 14, and one aged 15, all from Toxteth, have been arrested on suspicion of murder.
Staff at Ava's school, Notre Dame Catholic College in Everton, are working to support students.
Members of the public react after the death of Ava White, who was killed in Liverpool.
The headteacher described her as "a much loved, valued and unique member of the Notre Dame family" and has offered his prayers to her family and friends.
Police cordoned off a large part of Church Street near to Primark and the surrounding area following the incident on Thursday 26 November.
Officers are also carrying out fingertip searches in and around Williamson Square.
Assistant Chief Constable Jon Roy, said: "Our thoughts and condolences go out to Ava’s family, who are being supported specialist Family Liaison officers.
"Their world has been torn apart and no parent should ever have to face that knock on the door from police officers to say that their child has died."
A post mortem will be carried out to establish the cause of death.
The incident took place just a few hours after the Christmas tree lights switch-on in the city centre.
Anyone who witnessed the incident, or who has information which could help police with their enquiries, is asked to DM @MerPolCC or @CrimestoppersUK on 0800 555 111 with reference 0899 of 25 November.
An extensive cordon remains in place at the scene - which includes Williamson Square, Tarleton Street, Church Street, Church Alley, School Lane crossing over Hanover Street on to Fleet Street.
Shops including Marks & Spencer, Primark and Lush on Church Street, one of the city's main shopping streets, were closed on Black Friday due to the police cordon.
Councillor Sarah Doyle, Assistant Mayor, Violence Against Women and Girls, said: "I am heartbroken to hear that Ava White has died.
"I know news of this tragedy will shake communities across our city. My thoughts are with Ava’s family, friends and school.
"We will do all we can to support the city and those affected over the coming weeks."
Ava died on White Ribbon Day, a global campaign to end violence against women.
Assistant Chief Constable Jon Roy added: "Ava’s death should be a reminder to us all about the part that we each have to play in eliminating violence against women and girls.
"Ava died on White Ribbon Day which is a global campaign to end violence against women, and yesterday partners from around the city joined together to mark the day, which is also the start of 16 days of activity designed to raise awareness of VAWG and show how we are working together to make sure that VAWG is something that should not be tolerated in any society."