Detective Superintendent Sue Coombs of Merseyside Police said police were sharing a still image of a van which was in the vicinity of the incident which led to the death of Ava White

Detectives investigating the death of 12-year-old Ava White in Liverpool city centre have issued an image of a van which may have been occupied by key witnesses to the killing.

Ava White, a Year 8 pupil, was pronounced dead at Alder Hey Children’s Hospital after being stabbed in Liverpool City Centre at around 8.39pm on Thursday.

The “unique” and “incredibly popular” girl was in the area around Church Street with friends when she became involved in an altercation with another group of males.

Detective Superintendent Sue Coombs of Merseyside Police today said police were sharing a still image of a van which was in the vicinity of the incident, and may have witnessed something vital.

“To be clear, we think those vehicle’s occupants are witnesses, and in no way suspected of being involved,” she said.

“However, we still need to speak to those people as soon as possible to confirm what information they might hold.”

Police also issued new images of Ava on behalf of her family, and Ms Coombs said: “Our thoughts and condolences go out to Ava’s family, friends and the wider community.

“Ava’s family are being supported by specialist officers and they have requested that their privacy is respected at this difficult time.

“Merseyside Police is absolutely determined to bring those responsible to justice,” Ms Coombs said.

Four boys – one aged 13, two aged 14 and one aged 15, remain in custody for questioning, and part of the city centre remains cordoned off while police investigate.

Det Supt Coombs and Assistant Chief Constable Ngaire Waine held a briefing with the media at the new Police HQ, and confirmed a knife is believed to have been the weapon used.

Police also confirmed they are not looking for anyone else and that it is an isolated and rare incident.

Det Supt Coombs said she would “like to take this opportunity to remind people not to make any comments on social media which might potentially jeopardise our investigation, including of course names of any people potentially involved.

“We welcome any such information, but please only pass it on in the following ways so we can continue to make progress in our investigation.”

The four men, who were all from Toxteth, had been arrested on suspicion of murder and would be interviewed in Merseyside police stations going forward.

She said the force could not yet comment on whether Ava and her attackers were known to each other, but said: “There’s clearly a lot of CCTV in Liverpool city centre, so we are able to say there’s been a verbal argument and there has been an assault.

“The offenders have run off up School Lane, across Hanover Street, and into Fleet Street.

“Some of the difficulties are that a number of the witnesses are young people, and have been extremely distressed.

“The rest of the detail may take a little bit longer to come out; because we must treat those child witnesses very carefully, today and throughout the weekend they will need special treatment where we interview them with appropriate adults etc.

“We have yet to speak to any of the real key witnesses, the children, properly, but they will probably fill in those blanks.”

She confirmed the suspects were arrested “promptly” at different locations in the city up until the early hours of today.

Det.Supt Coombs said teams of detectives would be trawling through “hundreds of hours of CCTV”.

She said: “A lot of the evening was captured on CCTV, I think it will be, of differing qualities is probably the only real accurate way to describe it.

“It literally will be hundreds of hours of CCTV because of so many cameras, and obviously the timescale we will be interested in from when they first arrived in the city centre all the way through to the last arrests.”

The force is also urging anyone who may have mobile phone footage of photos from around the time of the stabbing to get in touch.