Graham Robb, head of the Youth Justice Board for England and Wales, said schools should be at the forefront of tackling the problem.
But he said some heads worry that taking part in prevention activities such as weapon searches could be seen as them having some kind of problem.
"There are ways to make sure young people are challenged and that orders of court are enforced."
The call for greater involvement by schools follows a spate of killings of school-aged children, including the shooting last week of 11-year-old Rhys Jones in Liverpool.
Heads in the city are expected to meet after the new term starts to discuss how to deal with the issue. But Mr Robb said schools did not always realise how much support was available from youth offending teams and the police.
Phil Hearne, the former head of the London Academy in Edgware, London, where pupil Kiyan Prince was stabbed to death outside the school gates last year, said schools should not be afraid of using guards and doing pupil weapons searches.
Gang culture, pages 4-5