Mark Duggan's family have said they will fight for justice after an inquest jury concluded by a majority of 8 to 2 that he was lawfully killed by police.
Mr Duggan was shot dead by armed officers in August 2011 in Tottenham, sparking riots across England.
Following the inquest at the Royal Courts of Justice, his aunt Carole Duggan said he had been "executed".
Metropolitan Police Commissioner Sir Bernard Hogan-Howe has asked for a meeting with local community leaders.
There were angry scenes outside the court, with supporters of Mr Duggan's family chanting "murderers" at Assistant Commissioner Mark Rowley as he read a statement.
Jurors concluded Mr Duggan did not have a gun when he was shot by officers who surrounded a minicab he was travelling in.
But the jury said it was more likely than not that he had thrown a gun on to some nearby grass just before he was killed. The weapon was found about 20ft (6m) away from the scene.
The panel of seven women and three men was asked to answer five questions:
- In the period between midday on 3 August 2011 and when state amber was called at 6.00 pm on 4 August 2011, did the Metropolitan Police Service and the Serious Organised Crime Agency do the best they realistically could have done to gather and react to intelligence about the possibility of Mr Duggan collecting a gun from Mr Hutchinson-Foster? The jury said a unanimous no.
- Was the stop conducted in a location and in a way which minimised, to the greatest extent possible, recourse to lethal force? Unanimous yes.
- Did Mr Duggan have the gun with him in the taxi immediately before the stop? Unanimous yes
- How did the gun get to the grass area where it was later found? A majority of 9 to 1 said it was thrown.
- When Mr Duggan received a fatal shot, did he have the gun in his hand? A majority of 8 to 2 said no, he did not have a gun in his hand.
Following the verdict his mother, Pamela Duggan, was led out of the court in tears, while Mr Duggan's brother was seen screaming and shouting.
BBC News home affairs correspondent Dominic Casciani tweeted: "I don't think I have ever heard of a jury, performing their civic duty, being abused in court by members of the public."
Following the conclusion to the inquest, an Independent Police Complaints Commission (IPCC) spokesperson said: "We note the inquest jury's determination and findings and we are considering them as a matter of urgency in relation to our ongoing investigation."
'No justice, no peace'
Outside court, his aunt Carole Duggan said: "The majority of people in this country know that Mark was executed.
"We're going to fight until we have no breath in our body for justice for Mark, for his children, and for all of those (unclear) with deaths in custody that have had nothing.
"We are not giving up. No justice, no peace!"
But Met Police Commissioner Mr Hogan-Howe said: "I welcome the verdict of a jury that our officers acted lawfully when they confronted an armed criminal who they believed posed a threat to them and to the public.
"The death of Mark Duggan in 2011 was a tragedy for his family and led to a significant reduction in trust between London's black communities and the Metropolitan Police.
"I know that we have much work to do with black Londoners to build trust and confidence in the Metropolitan Police.
"I have asked some of the capital's political representatives, and local community leaders from Tottenham, to meet me tomorrow [Thursday] to discuss how the Metropolitan Police can build better relationships for the future."
'Shot on sight'
The Duggan's family lawyer Marcia Willis Stewart said "We can't believe this was the outcome. He had no gun in his hand, yet he was shot, he was murdered.
"To us, that is unlawful killing."
In a statement later, Ms Stewart said: "The jury has found that Mark Duggan was unarmed at the point at which he was shot.
"We cannot countenance a situation in which an unarmed citizen is shot on sight.
"The jury found that there were failings in the way the police conducted the gathering and actioning of evidence. Had they done their job properly, this fatal shooting could have been avoided.
She added the family would seek an urgent meeting with the IPCC, their MP David Lammy, and MP Keith Vaz, in order to ensure the IPCC "carry a vigorous review".
Deborah Coles, from the charity Inquest, said Mr Duggan's family were considering whether to apply for the decision to be judicially reviewed.
Outside court, Assistant Commissioner Rowley attempted to read a statement which said the force had sympathy with Mr Duggan's family.
"No officer sets out at the start of the day to run an operation that results in someone dying," he said.
"We send out well-trained, professional armed officers thousands of times a year to combat this threat [of gun violence], only firing shots once or twice. These careful tactics have significantly reduced gun crime."
He added: "We know the trust is not shared by everyone. I will be offering to meet Mark Duggan's family to express our sorrow."
Tottenham MP David Lammy said the IPCC investigation had questions to answer, in particular what happened days before the shooting.
He said: "The Duggan family's sorrow and anger was palpable in court this afternoon and it is a feeling that will inevitably be reflected in the wider community.
"Further clarification on the events surrounding Mark Duggan's shooting is essential to enable the relationship between the community and the police to move forward.
"There are aspects of this verdict that are somewhat perplexing and seemingly contradictory to those of who us who have carefully followed the proceedings over the last few months."
A Home Office spokeswoman said it was "inappropriate to comment" while the IPCC was still carrying out its investigation.
BBC News correspondent Tom Symonds, who is in Tottenham, said the area was "very calm but has a high police presence".
The Met said there was an operation in place across London this evening where they have the ability to deploy extra officers if needed.
After Mr Duggan was shot, rioting spread across London and other parts of England in what became some of the worst disturbances in decades.
The inquest began in September. Before the jurors retired for what was seven days of deliberation, Judge Keith Cutler told them to reach their decisions "on the evidence and the evidence alone".
The coroner thanked the jury and told them they will be excused from future jury service for life if they want.