Number 10 has refused to comment on the shooting of an unarmed Black man by a police officer due to the period of national mourning for the Queen.
Chris Kaba, a 24-year-old rapper, was shot dead by police in Streatham Hill on 5 September.
The Metropolitan Police has said Kaba was stopped because his car was flagged by an automatic number plate recognition (ANPR) camera, which they say was associated with firearms.
The Audi he was driving was hemmed in by two police vehicles in Kirkstall Gardens, a narrow residential street, and one round was fired from a police weapon.
On Monday, the Independent Office for Police Conduct (IOPC) opened a homicide inquiry after mounting pressure, and announced the police officer responsible had been suspended.
On Tuesday, when asked about the killing, Number 10 said it would be inappropriate to comment during a period of national mourning for the Queen.
"What would you say to the family [of Chris Kaba] who believe he wouldn't have been killed if he was not Black?" a journalist asked at a briefing.
A Number 10 spokesperson said in response: "I wouldn't comment during a period of national mourning - nor while there's a live IOPC investigation."
Kaba's father, Prosper, has said racism played a rule in the killing of his son - who was about to become a father himself.
"For us, it is totally racist and criminal and we want all the community, especially the minority community, to see this as a racism case," he said.
Helen Nkama, his mother, said: "My heart is broken. I am speechless."
The Met Police has urged any witnesses to the killing to come forward, with assistant commissioner Amanda Pearson saying it has had a "significant impact on public confidence".
"Our thoughts and sympathies remain with Mr Kaba's family and friends," she said.
"We understand how concerned communities are, particularly Black communities, and thank those who are working closely with our local officers."
On Saturday, thousands of people marched on parliament, including music artist Stormzy, demanding justice.
Among the placards on the protest were "justice for Chris Kaba" and "no justice, no peace".
“I just encourage everyone to have stamina," Stormzy said at the march.
"I know it’s a very difficult thing to say because no one should have the stamina to go on a journey like this to get justice or to get answers, but when these people do these things, they get away with it.”
Diane Abbott, MP for Hackney North, said: “I don’t know how I would feel if it was my own son killed in cold blood.
"Chris is not the only Black man gunned down by the Metropolitan Police.”
Sadiq Khan, mayor of London, said it was a "welcome decision" that the police has launched an investigation.
“I welcome this decision and am in regular contact with the IOPC and the new commissioner," said Khan.
“My thoughts remain with Chris Kaba’s loved ones at this intensely difficult time as the IOPC continue their independent homicide investigation.”
In 2020, Met Police figures revealed it is four times more likely to use force against Black people compared with the white population.
Figures from the Home Office in 2020 revealed Black people in England and Wales are five times more likely to have force used against them than white people.
It also found Black people are seven times more likely than white people to have tasers used against them.
Watch: Chris Kaba: IOPC launches homicide investigation into fatal shooting by Met Police officers