Anger has boiled over in the western Mexican state of Guerrero over the government’s handling of the abduction and apparent massacre of 43 students.
Demonstrators set fire to the state’s congress and vehicles were torched.
The trainee teachers disappeared in the nearby town of Iguala more than six weeks ago after a confrontation with police.
At one point the state’s education department was broken into.
The disappearance of the students and the links it has revealed between local government and a drugs gang has triggered unrest for weeks.
Many believe the connections go far beyond regional level.
In the capital, protesters pointed a finger at national government. Some refuse to believe that human remains found in mass graves are those of the students and accuse the government of failing to give a full explanation of what has happened.
The case has plunged President Enrique Oena Nieto’s government into its biggest crisis.
Investigators have said that local police officers have confessed to seizing the students who had been holding a protest, and later handing them over the a gang calling itself Guerreros Unidos (United Warriors). The gang is said to have killed them and incinerated their bodies.