A van containing 16 of the bodies was plastered with a banner referencing the ongoing wars between rival drug cartels in Sinaloa, authorities said.

Four decapitated bodies were found hanging from a bridge in the capital of western Mexico's Sinaloa state on Monday, part of a surge of cartel violence that killed 20 people in less than a day, authorities said.

Twenty bodies, several of them decapitated, have been found on a highway bridge in the northwestern state of Sinaloa, Mexican authorities say, as rival drug cartel factions fight one another in the area.