Teachers protesting against an education overhaul have stormed the offices of political parties in southwestern Mexico, breaking windows and setting fire to the ruling party's offices.
Plumes of black smoke billowed from the rectangular-shaped headquarters of the ruling Institutional Revolutionary Party (PRI) in Guerrero state after masked protesters broke into the building and tossed chairs, papers and plants from windows.
Some spray-painted anti-government graffiti on the building, while others tore pictures of President Enrique Pena Nieto, who pushed through a reform plan for the country's failing education system with the backing of opposition parties.
Teachers in Guerrero are fighting the legislation that will impose tougher oversight of teaching standards and crack down on abuses.
The law takes away control of teacher assessment from a powerful teachers union and seeks to end the practice of teachers passing on posts to relatives or simply selling them.
'Traitors of the people'
Thousands of members of a teachers' union marched in the state capital, Chilpancingo, and groups wearing masks took their anger out on the offices of the PRI and three other political parties.
The protesters used pipes and sticks to destroy windows and doors at the local headquarters of the National Action Party (PAN), the Democratic Revolution Party (PRD) and the Citizen Movement. Protesters wrote "traitors of the people" on the PRD's walls.
Teachers have held several protests in recent weeks, twice blocking the highway between Mexico City and the Pacific resort of Acapulco to denounce the reform that passed the federal Congress in December.
The latest demonstration erupted one day after the Guerrero state legislature approved an education bill that fell well short of protesters' demands to water down the federal law, which requires teachers to pass periodic tests to get jobs and promotions.
Al Jazeera's Rachel Levin, reporting from Mexico City, said that protesters were upset because one of the main components of the reform is that teachers will lose their jobs if they do not pass evaluation.
"The teachers in Guerrero asked for their congress to exlude that clause from the reform and the politicians ignored their request," she said.
"So the teachers joined forces with the many vigilante groups in the state of Guerrero and they have been taking to the streets for over a week."
Chilpancingo Mayor Mario Moreno asked for federal security support to control the situation.
"We as a municipality do not have the ability to face a mob of 4,000 or 5,000 people," Moreno told Milenio TV.
Meanwhile, students in schools to become teachers blocked two federal highways in the neighbouring state of Michoacan, demanding that graduates from their college automatically get teaching positions.
Protests have also taken place in recent weeks in Oaxaca, which is among the country's poorest states along with Guerrero and Michoacan.