Officers arrest 450 in knife crime operation
25 June 2014 Last updated at 22:08 BST
About 5,800 officers across London arrested 450 people during a Metropolitan Police operation targeting knife crime.
Operation Big Wing is looking into a range of crimes, including robbery, burglary and gang crime.
BBC London's Warren Nettleford spoke to Det Chief Supt Gordon Allison from the Metropolitan Police and Professor Ben Bowling, a criminologist at King's College London.