Mexican officials say gunmen have killed at least 10 police officers and a civilian in an ambush in the the western state of Sinaloa.
Authorities say Friday's attack happened near the town of Guasave when the officers were returning from a political event in Los Mochis.
The French news agency, AFP, says the officers belonged to a security detail of Sinaloa's public security secretary, Francisco Cordova, who was not traveling with the convoy at the time of the attack.
Sinaloa has been the site of bloody confrontations among leading Mexican drug cartels feuding over lucrative narcotics supply routes leading to the united States.
Drug-related violence has become commonplace in Mexico, with about 37,000 people killed since the government launched an anti-drug crackdown in 2006.