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.

Violence has soared in Sinaloa since the capture in the U.S. of cartel co-founder Ismael "El Mayo" Zambada almost a year ago.