Hundreds of protesters in the Mexican state of Guerrero have attacked government buildings in the capital, Chilpancingo, burning cars.
They accused the government of involvement in the murder of 43 students in the town of Iguala in September.
The protest came after the attorney general said gang members had confessed to the killings. He said the students were killed by the criminals acting on police orders.
Mexican Attorney General, Jesus Murillo Karam said three alleged gang members had claimed the students were handed over to them by police. They said some were already asphyxiated and they shot the others dead, before setting fire to all the bodies.
The suspects from the Guerreros Unidos drug gang were recently arrested in connection with the disappearances.
Mr Murillo warned that it would be difficult to identify the charred remains and that authorities would continue to consider the students as missing until DNA tests confirmed the identities.
Mr Murillo showed videotaped confessions by the suspects who said they had loaded the students into dumper trucks and taken them to a landfill site in Cocula, a city near Iguala.
About 15 of the students were already dead when they arrived and the rest were shot, according to the suspects.
Mr Murillo said the bodies were then burned with petrol, tyres, firewood and plastic in an inferno that lasted for 14 hours.
The protests on Saturday in Chilpancingo echoed weeks of protests across the country where demonstrators have insisted there is collusion between officials and organised crime, along with government inaction. Masked protesters were armed with petrol bombs in Chilpancingo.
The missing students from a teacher training college in Ayotzinapa in Guerrero state had travelled to nearby Iguala to protest against what they said were discriminatory hiring practices, and to collect funds for their college.
But they went missing after clashes with the police.
More than 70 people have been arrested in connection with the disappearances, including the Mayor of Iguala, Jose Luis Abarca, and his wife, Maria de los Angeles Pineda, who were detained in Mexico City last Tuesday.
(Source: BBC World)