San Francisco (AFP) - US President Barack Obama voiced confidence Friday that a "shocked and heartbroken" nation would eventually tighten permissive gun laws, striking a more strident tone after the deadly Charleston shooting.Obama told US mayors in San Francisco that change would come one day, as he took on detractors who accused him of politicizing the deaths of nine black worshippers in South Carolina.Describing gun crime as a crisis that "tears at the fabric of a community" and "costs this country dearly," Obama said:"More than 11,000 Americans were killed by gun violence in 2013 alone. 11,000."He accused Congress of failing to act after a mass shooting in Newtown, Connecticut, in 2012 which killed 26 people, including 20 children, at Sandy Hook elementary school."We wouldn't have prevented every act of violence or even most," Obama said."We don't know if it (gun reform) would have prevented what happened in Charleston. No reform can guarantee elimination of violence, but we might still have some more Americans with us."We might have stopped one shooter, some families might still be whole. You all might have to attend fewer funerals."In the immediate aftermath of the Charleston shooting Obama had voiced resignation that change would not come in the autumn of his eight-year term in office.On Friday he sounded more resolute and called for an honest debate."At the very least we should be able to talk about this issue as citizens. Without demonizing all gun owners who are overwhelmingly law abiding, but also without suggesting that any debate about this involves a wild-eyed plot to take everybody's guns away," he said."I'm not resigned. I have faith we will eventually do the right thing," he said."We have the capacity to change, but we have to feel a sense of urgency about it."Join the conversation about this story Click here to read full news..