Hillary Clinton has attacked her main rival Bernie Sanders over US gun laws at the Democratic presidential debate, reports BBC.When asked if the Vermont senator was strong on gun control, she said "no, not at all" before vowing to go after the makers of guns used in shootings.Mr Sanders also attacked Mrs Clinton, saying her support for a no-fly zone in Syria would create "serious problems".His rallies have drawn big crowds and he has challenged Mrs Clinton`s frontrunner status in some key states.A lot of the key exchanges came between these two, and the three other candidates on stage in Las Vegas - former Maryland Governor Martin O`Malley, former Virginia Senator Jim Webb and former Rhode Island Senator Lincoln Chafee - struggled to make headway.