Murder squad detectives are continuing to question four people on suspicion of the murder of 11-year-old Rhys Jones.
The four - all males, aged 24, 20, 17 and 16 - were arrested in Liverpool on Friday morning as the officer leading the inquiry urged a mystery caller to come forward.
Rhys died in Alder Hey Children's Hospital after being shot through the neck on Wednesday, August 22, by a teenage gunman.
The new arrests take the total number of people arrested on suspicion of murdering the 11-year-old to 16.
Seven people were arrested and released on police bail with a further five being arrested and released without charge. These five are now being treated as witnesses.
Assistant Chief Constable Patricia Gallan said: "Detectives have this morning arrested a further four people in connection with the ongoing investigation into the death of 11-year-old Rhys Jones.
"Arrests made so far are based on consistent information from callers and round-the-clock inquiries by detectives.
"Whilst this inquiry progresses swiftly, it is very much part of a focused, clear and confident investigation strategy. All individuals arrested so far are absolutely critical to the inquiry.
"People are aware that we have described one individual firing a gun but, as with any offence, there are various stages and elements to it, such as where the gun came from and what occurred afterwards. When we have grounds to suspect people involved in any stage, they will be arrested in connection with this offence."
On the day Rhys's family released details of his football-themed funeral, Detective Superintendent Dave Kelly appealed for a mystery caller to contact him. He said the caller phoned Crimestoppers last Friday with "significant" information about seeing a male talking on a mobile phone.
