Ava White had been in the city with friends on Thursday following a Christmas lights switch-on when she suffered "catastrophic injuries" in an assault, Merseyside Police say.

A 14-year-old boy, who cannot be named for legal reasons, has been charged with murder and possession of a bladed article.

He has been remanded in custody to appear in court on Monday.

Three other boys aged between 13 and 15, who were also arrested, have been conditionally bailed as inquiries continue.

Ava, who has been described as "popular" and "bright", was involved in a "verbal argument" which escalated into an "assault on her with a knife", police say.

The offenders fled and Ava was taken to hospital after paramedics arrived but died a short time later.

On Friday, flowers were being laid on Church Street in tribute to the Notre Dame Catholic College pupil, as forensics officers and police searched the scene.

A balloon was left by 17-year-old Lacey, who did not want to give her surname, who said her younger sister had been close friends with Ava.

She said: "She was just a bubbly character, so loving and caring.

"She came out with her friends to enjoy herself and I think it's just wrong that this has happened."

Headteacher Peter Duffy said: "She was an incredibly popular girl with a fantastic group of friends."

Assistant Chief Constable Ngaire Waine said the incident was "sad for the city" but "even sadder" for Ava's family.

On Saturday, police issued an image of a van that may have been occupied by key witnesses to the killing.

Australian Associated Press