Protesters in Mexico have attacked the local government headquarters in the state of Guerrero in anger at the disappearance of 43 students.
Hundreds of demonstrators broke windows and set fire to part of the building in the state capital, Chilpancingo.
The students have been missing since clashes with police on 26 September in the town of Iguala.
Several officers accused of colluding with a drug gang were arrested after the violence, in which six people died.
The protesters allege that the police rounded up the missing students before handing them over to a local drug gang called Guerreros Unidos.
Demonstrators gathered outside the government complex in Chilpancingo on Monday, allowing workers to leave before ransacking and setting fire to the building and a vehicle parked outside.
They are calling for Governor Angel Aguirre to resign over the disappearance of the students and have vowed to "radicalise" their actions if there is no progress in the investigation.
Thousands of people have taken to the streets across Mexico to demand government action to locate the missing students.
President Enrique Pena Nieto went on national television at the weekend to promise to identify and punish those responsible for the disappearances.
He described the incident as "shocking, painful and unacceptable" and said there will be "no impunity".
The Guerreros Unidos gang has been linked to the family of Iguala's Mayor Jose Luis Abarca Velazquez.
He, his wife and his head of security went on leave after the clashes and have not reappeared. A formal search has been launched for them.
Authorities are investigating whether the students were killed and buried in several mass graves found outside Iguala, some 200 km (125 miles) south of Mexico City.
Governor Aguirre said on Saturday that the students were not among the bodies identified so far from 28 burnt corpses recovered from the graves.
"I have big hopes of finding our young students alive," he told reporters.
Prosecutors have detained 26 police officers in connection with the clashes on 26 September, as well as four gang members and four other unidentified people.
The students all attended a local teacher training college with a history of left-wing activism but it is not clear whether they were targeted for their political beliefs.