The meeting brought together youth leaders, academics, politicians, film and media and Internet representatives in what was described as a "brainstorming session" intended to review the issues, but not point blame.
Two gun manufacturers' bodies sent delegates, but the National Rifle Association (NRA), the firearms lobby group, was not invited. The manufacturers had met a presidential adviser, Bruce Reed, last week and agreed in principle to support tougher curbs on firearms, including possibly raising the age at which someone can buy a gun from 18 to 21.
The NRA held a press briefing in Washington before the summit to argue that stricter controls would not have prevented the Colorado slaughter, and that existing laws could be more effectively enforced. The two gunmen, an NRA spokesman said, "broke 18 laws on the books; you could pass 50 new laws, but bad people would still do bad things". A Gallup poll showed a majority in favour of further gun controls and regulating the Internet to restrict access to violent material.