Mexicans furious at the presumed massacre of 43 students torched the ruling party's Guerrero state headquarters and briefly took a police commander prisoner Tuesday as growing protests rocked President Enrique Pena Nieto's government.
Riot police clashed with protesters in running street battles as black smoke billowed from the white two-story building of the Institutional Revolutionary Party (PRI) in the southern state's capital Chilpancingo.
Violent protests have erupted in Mexico since authorities said Friday that gang hitmen confessed to murdering the students and incinerating their bodies after corrupt police handed over the 43 young men in September in Guerrero state.
Some 1,000 people, including students and members of the radical CETEG teachers union, marched in Chilpancingo before battling police, throwing stones and firebombs.
Three officers and two journalists were injured after being struck by rocks, a civil protection official told AFP. One of them is a photographer working for AFP.
"The vandalistic assault on our building is more than an attack against this political party. It is an aggression against Guerrero's society and represents a threat to people that should not be repeated or left unpunished," the PRI said in a statement.
Workers were able to flee the building, which had undergone renovations after it was torched last year by protesters angry at a controversial education reform.
The protesters Tuesday also grabbed the state's deputy public security chief, Juan Jose Gatica, and held him for several hours before handing him to a local human rights group.
Roman Hernandez, spokesman for the Human Rights Center of Tlachinollan Mountain, told AFP the protesters released the officer on condition that two detained teachers be freed, but that the pair had yet to be let go.
- Series of protests -
The apparent slaughter of the trainee teachers has undermined Pena Nieto's assurances that his security strategy was bearing fruit and reducing drug-fueled violence that has killed more than 80,000 people since 2006.
The crime has also hurt his efforts to shift Mexico's narrative away from drug cartel mayhem and toward economic and political reforms that have won international acclaim.
Pena Nieto was in China for a summit on Tuesday despite criticism over his decision to travel in the midst of the escalating crisis.
Protesters besieged the airport of Guerrero's Pacific resort of Acapulco for three hours on Monday, forcing three flight cancellations, after clashing with police.
On Saturday, a group of 20 demonstrators briefly set fire to the wooden door of the National Palace in Mexico City at the end of a march that had drawn thousands of people.
- Meeting with families -
 Authorities say gang-linked police shot at busloads of students in the Guerrero city of Iguala on September 26, in a night of violence that left six people dead.
The police then handed the 43 abducted students to the Guerreros Unidos drug gang, prosecutors say.
Authorities say Iguala's mayor ordered police to confront the students over fears they would interrupt a speech by his wife, who aspired to succeed him.
The students had traveled to Iguala to raise funds but hijacked four buses to return home, a common practice among the young men from the college known for its radical left-wing politics.
Officials stopped short of declaring the students dead, stressing they were waiting for DNA results.
Parents of the missing students, who deeply distrust the government, say they will only believe their sons are dead once they get independent DNA test results.
Interior Minister Miguel Angel Osorio Chong and Attorney General Jesus Murillo Karam met with the families at the Chilpancingo airport.
Pena Nieto was in Beijing for an Asia-Pacific Economic Cooperation (APEC) summit and a state visit.
After China, a country with which he has sought closer ties, Pena Nieto will travel to Brisbane, Australia, for the summit of the Group of 20 major economies. He comes home Saturday.