The New Yearís Eve party was going well until someone trod on the toe of another reveller.
The offending person refused to apologise, a gun was produced, and two people died.
The shooter has not been caught.
Itís just one example of how guns are being used in what has become known as "black-on-black" crime.
In some parts of London, according to the police, some young men now carry firearms routinely.
The message coming from the media and some politicians is that young black men are potential criminals
The Commission for Racial Equality
The guns are not just for show. They are loaded, and they are being used to settle arguments, sometimes over issues of "respect".
Last year in London, there were 156 shootings within the black community, an increase of 96% on the previous year. The total included 19 murders.
So far this year, there have been 65 firearms incidents, up more than 60% on the same period last year. Eight people have died.
Scotland Yard set up Operation Trident to try to halt the rise in these "black on black" shootings.
At the head of a team of 230 police officers, Detective Chief Superintendent Andy Sellers has seen the emergence of a gun culture in some sections of the black community.
"The people we come across seem to carry firearms fairly routinely; a gun is almost a piece of jewellery now," he says.
Andy Sellers: Tackling gun crime
"They donít seem to have much care for other peopleís lives, even their own lives. We have seen gunfights where there is every chance they are going to end up dead.
"Perhaps in our younger days, in a dance hall, the worst you could expect was a black eye. Now there is an immediate recourse to firearms if they are available.
"I have heard black community leaders say they donít recognise the moral code being operated."
To discuss such crimes is to risk perpetuating stereotyped images of black people involved in drugs and violence.
Fear of crime
Beverley Bernard, deputy chair of the Commission for Racial Equality, says it is an image that annoys many young people.
"The message coming from the media and some politicians is that young black men are potential criminals," she says.
"There is an issue of crime in black communities, but there is a tendency to hype it and create fear. There are a lot of young black men holding down good jobs who are being smeared by this kind of blanket description."
The crime reduction charity, Nacro, points to government research that shows people from minority ethnic groups are no more likely to get involved in crime than white people.
Yet Scotland Yardís crime figures show that there is a serious problem with firearms in certain parts of London.
Behind all of this there is human misery. All of these victims have got families, friends and relatives
Policeman Andy Sellers
The police argue that for the media to ignore this type of crime, because it is happening largely within a minority community, almost amounts to racism.
Detectives say this gun culture is being driven by the drugs trade. Rivalry between competing gangs increasingly leads to death.
Once, these crimes were blamed on Yardie gangsters, importing a criminal way of life from Jamaica. Now, the majority of both victims and suspects are young men born and brought up in Britain.
The police admit that ten London boroughs now have a "gun crime problem".
Trying to make sense of shifting patters of crime is difficult.
What is obvious is that London and its people have changed over the past 20 years.
Crime and poverty
A recent study, "Policing for London", made the point that the capital has become more polarised between rich and poor, and much more diverse.
In the London boroughs, ethnic communities now make up 22% of the population, compared with 11% in 1981.
Some of the poorest minority groups contain a high proportion of young people living in high crime areas.
According to one estimate given to the CRE recently, half of Londonís young unemployed are black.
Partly as a result of "black-on-black" shootings, the borough of Lambeth has some of the worst figures for violent crime.
Over the past three years, there have been 38 murders, 17 in the last year alone.
While such figures may be exceptional, ethnic minorities across Britain are at greater risk of becoming victims of this type of crime.
Recent Home Office figures reveal that in cases of homicide, almost one victim in five is a member of a minority ethnic group.
The gang has become the family
Beverley Bernard of the CRE
In many cases, the perpetrator of the crime is from the same ethnic group as the victim. And in cases where the victim is black, the figures show the police are much less likely to identify a suspect.
Amid the gang wars of London, people are often reluctant to give evidence, fearing reprisals. The Operation Trident team is building up a witness protection programme.
"There is an understandable reluctance for people to come forward because of the ability of the gunmen to threaten and intimidate," says Detective Chief Superintendent Andy Sellers.
"But we sense a real desire in the black community to start to deal with it. They have had enough. They are saying it is a community problem, and saying they have to help the police to solve it."
To those who question whether the campaign is having any impact, he asks a question in return: how much worse would it be if the police werenít making this effort?
Last year alone, the Operation Trident team seized more than 200 firearms.
"Behind all of this there is human misery. All of these victims have got families, friends and relatives," he says.
Why the gang culture has become such a feature of life in some ethnic communities is a complex issue.
Beverley Bernard, of the CRE, believes that for some young black men, joining a criminal gang fills a gap in their lives.
"For those of us who live in the inner city, what you see is that the gang has become the family," she says.
"It is a response to the social and economic exclusion of these young men. It provides them with emotional support."
She argues that the government should be doing more to provide opportunities for young black men. And there should be greater support for families, instead of penalising parents whose children are not in school.
"It comes down to the life chances people have. If you want to be tough and tackle crime, you have to stop it getting rooted, and escalating, and not just build more prisons.
"There is a deep structural issue of how society deals with young black males. We cannot ignore it."