Enquiries revealed that the four were known members of an urban street gang and the youth they had targeted was linked to a rival gang.
Detailed analysis of the clothing worn by the suspects seen on CCTV chasing the victim showed exact matches for the four arrested shortly afterwards along with the weapons recovered.
Detective Chief Inspector Michael Herbert, who led the investigation, said: "The CCTV footage shows this terrifying incident unfolding on a Sunday afternoon in a residential area where it was witnessed by a large number of people including young children.
A converted blank-firing handgun along with four rounds of 9mm ammunition was found in a black Louis Vuitton man-bag in the neighbouring garden.
The group had walked three miles into an area associated with the rival gang apparently looking for any opposing gang member to target.
