Cars screech to a halt, horns blare and lights flash as a group of terrified youngsters run across the dual carriageway dodging traffic. Moments later a second group appears, hurling bricks, bottles and obscenities as they chase their prey into the maze of side streets and lanes that make up Drumchapel, once one of the largest council housing schemes in Europe. In trainers, baseball caps and tracksuits, many carry weapons - anything from golf clubs to kitchen knives - as they embark on the favourite sport of many of the youngsters from such schemes - recreational violence.
It has been another grim week for knife crime. During a bank holiday weekend when 50 knifing incidents were reported to police, Thomas Grant, a 19-year-old student, was stabbed to death on a train. Last Tuesday, Barry Wilson, a father of three, was stabbed to death in front of his children in Bristol. As the Home Secretary, John Reid, promised tougher sentences, new research from the Home Office suggested that nearly half a million young people belong to gangs in which weapons are rife, that there are now an estimated 100 violent incidents involving knives every day in England and Wales, and that one person a week is stabbed to death in Scotland.
The current UK amnesty on knives can only dent these terrifying statistics. It's business as usual on the streets of Europe's knife capital, Glasgow.
Almost 150 years after they were first documented and 80 years since they earned Glasgow the "no Mean City" label, its gangs are more numerous and violent than ever. Throughout Glasgow, a city of little more than 1 million people, there are estimated to be more than 170 gangs, accounting for more than 2,000 hard-core members and numerous other hangers-on.
Each roams the city fighting pitched battles with knives, clubs, bricks and bottles over graffiti-daubed streets in an epidemic of violence so widespread in the west of Scotland that one in six reported assaults involves a blade. But doctors have admitted that the vast majority of stab wounds treated in the city's hospitals go unreported to the authorities. The scale of the violence is feared to be much greater than officially acknowledged.
"Gang violence has sadly been an issue in the west of Scotland and Glasgow in particular for many decades," says Detective Chief Superintendent John Carnochan, head of the Violence Reduction Unit. "Some gangs date back 30 to 40 years. There are young men involved in the same gangs in which their fathers, brothers and uncles fought years ago and their rivalries too will have remained unchanged."
One of the few differences is that modern technology means fights are often pre-arranged on the internet or through mobile-phone messages allowing rival gangs, who might not otherwise have had regular contact with each other, to spread their hate over a wider area.
It is suggested that a fight which broke out in Glasgow's city centre during the civic Hogmanay celebration had been pre-arranged on the internet. Within minutes of the start of 2006 seven teenagers had been stabbed after they were caught up in a battle between rival gangs from Cowcaddens and Bridgeton.
Although most of the violence is directed against rival gangs it does occasionally spill out in the wider community creating a climate of fear. A recent survey by Mori found that thousands of Glaswegians were too afraid to venture into the city centre at night and that three-quarters of them felt the streets were unsafe after dark.
Last September the United Nation's crime research institute said Scotland was the most violent country in the developed world. Scots were nearly three-times more likely to be the victims of violent assaults than people living in the United States. More than 50 per cent of knives found by the police in Scotland are seized in Glasgow. Stabbings account for half of all murders.
Simon Leila has been teaching self defence for more than 20 years in cities across the UK and he admits he has been shocked by the level of knife crime. "In every class we teach in Glasgow there are at least a couple of people who have been victims of knife crime. When I was teaching in England I could go years without ever meeting anybody who had been stabbed or even threatened with a knife," says Leila whose organisation, Krav Maga Scotland, teaches a form of self-defence pioneered by the Israeli military.
"The vast majority of people we teach are ordinary members of the public who are anxious about violent crime. We spend almost 40 per cent of time in our Glasgow classes practising knife-defences because of the problem - that's double the time devoted to the problem in other areas of the country."
Photographer Colin McCreery and a friend chased off a teenager mugger outside a club in Glasgow only to meet up with their attacker and some of his friends an hour later.
"They didn't want my money the second time, they just wanted to kill me," says Colin, 32. "My friend managed to escape but I was surrounded by five of them and at least two had knives. There was no threat or demands they just started trying to stab me.
"I was stabbed in the back, but luckily the blade didn't hit any vital organs and I survived. I am convinced it was nothing less than attempted murder."
For the teenage gang members who stalk the streets of some of the most deprived areas in Europe, however, a knife is a symbol of power, defiance and protection. "I carry a knife because everybody else does," said one face-scarred teenager. In front of his jeering friends and fellow gang members, of both sexes, the youngster - "Danny" - who claims to be 16 but looks at least a couple of years younger, tries to explain why he needs a knife. In between draws on his cigarette, the shell-suited youngster claims it is for protection but admits that if faced with a rival gang member he wouldn't think twice about giving him a "plunge".
Faced with such a culture, where turf wars provide a shot of excitement, Strathclyde Police are fighting an uphill battle. Although pilot projects, including the provision of extra sports facilities for youngsters in areas such as Sighthill, where racial tensions between local gangs and asylum-seekers are a problem, have helped to reduce knife crime by about 70 per cent.
Attempts have been made before to tame the gang culture in Glasgow. In 1968 singer Frankie Vaughan tried to broker peace between the warring gangs of Easterhouse. In a highly publicised amnesty campaign, the performer, raised in poverty in the East End of London, persuaded youngsters to hand in their weapons in return for youth clubs and better facilities. But 40 years later, the grandchildren of those youths are once again squaring up to each other.
"Territorialism is very often the excuse for conflict," says Det Ch Supt Carnochan. "In most incidents it's violence for violence sake. On many occasions, those involved will be of school age and so gang rivalry then spills over into the school playground on a Monday morning.
"Although we have lived with this problem for decades, the time is now right to take action. We cannot allow gang fighting to go on untreated for another four decades. Everyone has their part to play. We need to offer youngsters innovative diversionary activities and a real chance to get employment, contribute to their communities and make something of their lives rather than becoming a police statistic.
"These young men are born and live in the communities in which they fight. If they survive it is likely they too will bring up their children in these same communities, as their fathers did."