The incident occurred on Thursday.
Four teenage boys in the UK have been arrested on suspicion of murdering 12 year old Ava White in Liverpool.
The girl died after an incident occurred in the city centre on Thursday night, according to Merseyside Police.
The young girl allegedly suffered "catastrophic injuries" after an assault that followed a verbal altercation at around 8.39pm, not long after the Christmas lights had been switched on, police said.
The four boys arrested are aged between 13 and 15, one being 13, two aged 14 and another aged 15.
https://twitter.com/MerPolCityCen/status/1464145734639497216
The girl was found collapsed on the ground with friends and being given first aid from a passerby when police arrived on the scene.
She was then taken to Alder Hey Children's Hospital in an ambulance but did not survive her injuries.
Assistant Chief Constable Jon Roy said: "Our thoughts and condolences go out to Ava's family, who are being supported by 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.
"We believe that Ava and her friends had been involved in a verbal argument which culminated in Ava being assaulted causing catastrophic injuries.
"And we understand that the offenders were then seen to run up School Lane across Hanover Street and on to Fleet Street.
"We have arrested four males aged, one aged 13 years, two aged 14 years and one aged 15 from Toxteth, on suspicion of murder and they are currently being interviewed at police stations on Merseyside.
"Liverpool City Centre was very busy at the time of the incident as the lights on the Christmas tree on Church Street had been officially switched on a short while earlier and we would appeal to anyone who was on Church Street who saw the incident, or may even have captured it on their mobile phone, to come forward."
Police are now looking for anyone who witnessed or filmed the incident to contact them either on Twitter at MerPolCC, Merseyside Police Contact Centre on Facebook or by calling Crimestoppers on 0800 555 111 with reference 0899 of November 25.
