A black community leader has appealed for information after the fatal shooting of a teenager in south London.
The victim, Sylvester Akapalara, 17, of Streatham, was shot in Peckham on Wednesday. Two males are being held. Three others have been freed.
Claudia Webbe, chairwoman of the Trident Independent Advisory Group, has urged the members of the black community to talk to police.
She said: "Silence is not an option - this is a call to action."
The investigation is being led by officers from Trident, which investigates gun crime in the black community.
The Trident Independent Advisory Group is a panel made up of members of the public which scrutinises its work.
Ms Webbe, who has spent a lifetime campaigning against racism and injustice, said: "The nature of violent crime involving guns is that the perpetrators rely on people keeping silent through fear of further violence.
"Over time Trident has successfully raised the level of confidence for people to speak out - but still we have not gone far enough.
"There are definitely a number of otherwise law-abiding people who for whatever reason are still fearful of speaking out."
She added: "We in the community need work with the police to bring the people who killed this young man to justice."
Police are linking Sylvester's death to the stabbings of two other teenagers nearby. One of them remains seriously ill in hospital.
He was a Sierra Leonian national.
Three teenagers were arrested shortly afterwards. Two of the three have been released with no further action to be taken, while the third has been bailed until January.
Two further youths arrested, aged 17 and 18, are still being questioned.
Ms Webbe said: "As a community we have to be shocked when we think about children living in fear, being gunned down in this way.
"Once a bullet has been fired everyone is at risk, because you do not know where that bullet will end up."
Police are investigating whether the violence was gang-related.
The teenager was found bleeding to death on the fourth floor of Heron House on the Pelican Estate.
Post-mortem tests showed he had been shot in the neck and chest.
A second 17-year-old boy was found with stab wounds in a flat in neighbouring Gannet House and an 18-year-old man went to King's College Hospital with minor injuries. Both have since been allowed home.
Territorial Policing Commander Jim Webster said: "The death of any young person in these circumstances is a tragedy for the family concerned and a shock to the wider community.
"This is a fast-moving investigation with further arrests having now taken place, but the impact of youth violence is a long-term issue which will take the work of all of us to combat."