Officials says 6 police officers killed in attack in Mexico

MEXICO CITY: Six police officers were killed by gunmen in the north-central Mexico state of Guanajuato, authorities said.

State Interior Secretary Gustavo Rodriguez Junquera said the dead officers were traffic police and he promised that "this crime will not go unpunished.

" Rodriguez Junquera did not say how the attack occurred, but local media reports said the officers were killed by shots fired from a passing vehicle.

Guanajuato was long a relatively peaceful state, but in recent years it has been plagued by crime gangs that rob freight trains and drill into state-owned oil pipelines to siphon off fuel.