A shootout between police and gunmen kills 12 people yesterday in the central Mexican state of GuanajuatoGovernor Juan Manuel Oliva says soldiers and federal and state police were on patrol when assailants opened fire.Oliva said arrests have been made but didn't give any other details.Mexico has been suffering a wave of gang violence that has left nearly 11 thousand people dead since President Felipe Calderon took office in December 2006, and launched a military-led crackdown on drug traffickers.