Mexico has been confronted with possibly one of the grisliest massacres in years of drug violence after gang suspects confessed to incinerating the bodies of 43 missing students and dumping them in a river.

The disappearance of the students six weeks ago has gripped and horrified Mexico.

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Gang-linked police attacked the young men in the southern state of Guerrero on September 26, in violence that left six other people dead.

The confessions may have brought a tragic end to the mystery, which has sparked international outrage and triggered protests in the biggest crisis of President Enrique Pena Nieto’s administration.

But at the young men’s Ayotzinapa teacher-training college, exhausted parents of the victims refuse to accept they are dead until DNA tests confirm their identities, saying the government has repeatedly fed them lies.

Three suspected Guerreros Unidos gang members told investigators that local police handed them the students between the southern towns of Iguala and Cocula.

In taped confessions, the suspects said they bundled the 43 in the back of two trucks, took them to a nearby landfill, killed them and used fuel, wood, tires and plastic to burn their bodies for 14 hours.

The students had travelled to the city of Iguala to raise funds but hijacked four buses to return home, a common practice among the young men from a school known as a bastion of left-wing activism.

Authorities say the city’s mayor, worried that they would interrupt a speech by his wife, ordered the police to confront them.

The officers shot at several buses, leaving three students and three bystanders dead.

Authorities have arrested 74 people, including the ousted mayor, Jose Luis Abarca, his wife Maria de los Angeles Pineda, 36 police officers and several Guerreros Unidos operatives.

If the confessions are true, the mass murder would rank among the worst massacres in a drug war that has killed more than 80,000 people and left 22,000 others missing since 2006.