MEXICO CITY (AP) — 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 nearly 20 people in less than a day, authorities said.

A bloody war for control between two factions of the powerful Sinaloa Cartel has turned the city of Culiacan into an epicenter of cartel violence since the conflict exploded last year between the two groups: Los Chapitos and La Mayiza.

Dead bodies appear scattered across Culiacán on a daily basis, homes are riddled with bullets, businesses shutter and schools regularly close down during waves of violence. Masked young men on motorcycles watch over the main avenues of the city.

On Monday, Sinaloa state prosecutors said that four bodies were found dangling from the freeway bridge leading out of the city, their heads in a nearby plastic bag.

On the same highway Monday, officials said they found 16 more male victims with gunshot wounds, packed into a white van, one of whom was decapitated. Authorities said the bodies were left with a note, apparently from one of the cartel factions, though the note's contents were not immediately disclosed.

Feliciano Castro, Sinaloa government spokesperson, condemned the violent killings on Monday and said authorities needed to examine their strategy for tackling organized crime with the “magnitude” of the violence seen.

“Military and police forces are working together to reestablish total peace in Sinaloa,” Castro said.

Most in the western Mexico state, however, say authorities have lost control of the violence levels.

A bloody power struggle erupted in September last year between two rival factions, pushing the city to a standstill.

The war for territorial control was triggered by the dramatic kidnapping of the leader of one of the groups by a son of notorious capo Joaquín “El Chapo” Guzmán who then delivered him to U.S. authorities via a private plane.

Since then, intense fighting between the heavily armed factions has become the new normal for civilians in Culiacan, a city which for years avoided the worst of Mexico’s violence in large part because the Sinaloa Cartel maintained such complete control.

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