Protesters smashed windows and set fire to a government building in southern Mexico, expressing fury over the disappearance of 43 young people believed abducted by local police linked to a drug cartel.
The demonstrations happened in Chilpancingo, the capital of the state of Guerrero.
On Monday, the demonstrators called for the 43 students from a rural teachers' college in Guerrero state, missing since Sept. 26, to be returned alive, even though fears have grown that 10 newly discovered mass graves could contain their bodies.
Protesters could be seen burning photos of government officials.
They also pushed over a delivery truck.
Smoke poured from the government buildings, with flames shooting from office windows.
The violence came more than two weeks after police in Iguala, also in Guerrero state, opened fire on the teacher's college students, killing at least six. Witnesses have said that dozens of students were taken away by police and have not been seen since. Twenty-six local police officers have been detained, and officials are attempting to determine if any of the students are in the mass graves nearby.
The confrontation in Iguala shed light on a widespread problem with local police in Mexico: They are often linked to organized crime. In the case of Iguala, the police who attacked the students were working with the local cartel, Guerreros Unidos, according to testimony of those arrested.
Monday's protests came after police in Guerrero shot and wounded a German university student in a reported case of mistaken identity, prosecutors said.
The victim, Kim Fritz Kaiser, is an exchange student at the Monterrey Institute of Technology, Mexico City campus, said institute director Pedro Grassa. He told Milenio television Monday that Kaiser is in good condition and that that injury was not grave, though Kaiser will remain under observation.
A U.S. State Department travel warning issued last week said U.S. citizens should avoid Chilpancingo along with all parts of Guerrero state outside of the Pacific resorts of Acapulco, Ixtapa and Zihuatanejo and the tourist attractions of Taxco and the Cacahuamilpa caves.
A previous warning in January already advised against travel in the northwestern part of the state near the border with Mexico state, where Iguala is located.
The Associated Press contributed to this report.