The mother of a 15-year-old boy attacked by a group of youths said she heard the gunshots that killed him.
Keon Lincoln was "set upon" at about 15:30 GMT on Thursday on Linwood Road in Handsworth, Birmingham, and died later in hospital, police said.
In an emotional appeal, Sharmaine Lincoln pleaded with the local community to "help us understand why this has happened".
Five teenage boys have so far been arrested over his death.
A post-mortem examination revealed Keon was shot and stabbed to death.
Remembering that afternoon, Ms Lincoln said: "I heard the gunshots and my first instinct was, 'Where's my son?'
"A few minutes went by, we heard somebody was in the road and it was my boy."
West Midlands Police arrested three teenagers over the weekend on suspicion of Keon's murder - a 14-year-old boy from Birmingham and two others, aged 15 and 16, at an address in Walsall.
This is in addition to two 14-year-old boys arrested on Friday, one of whom remains in custody and the other released under investigation.
Det Ch Insp Alastair Orencas, from West Midlands Police, said the attack on Keon was "the most pointless use of extreme violence I've witnessed in my 24 years in the police force".
"The level of violence has not just caused shock to the family, but to hardened police officers," he said. "It was an absolutely pointless attack, one I can't clear my mind of."
The force is appealing for information and Det Ch Insp Orencas said the community response was "not where it should be".
"These are multiple offenders in broad daylight. I simply don't believe there's not information out there that can help me with the inquiry," he said.
Ms Lincoln remembered her son as a joker, cheeky - a "loving child with a jolly spirit" whose "unbelievable laugh" would echo daily around her home.
"It doesn't make sense, the type of person Keon was, it doesn't make sense as to why someone would want to harm him or take his life in such a brutal way," she said.