Protesters in southern Mexico set fire to the state government building on Monday and burned at least twelve cars in the parking lot.

The protests took place in the violence-torn city of Chilpancingo, the capital of the Pacific coast state of Guerrero.

The protesters are demanding answers in the case of the disappearance of 43 students from the Rural Teachers' College in 2014. Another student from that college was killed in a confrontation with police in March.

The Guerrero state government said in a statement that it “regrets and condemns the acts of violence,” noting that the state interior minister resigned after the confrontation with students in March, and that investigations are ongoing into the police officers involved in the death.

Images of the protests showed at least 12 cars burning and flames coming out of the windows of the government office building located near the main highway leading from Mexico City to Acapulco. The building, which houses the governor's office, was looted.

Students at the radical Teachers' College in Ayotzinapa, located on the outskirts of Chilpancingo, are known for their violent protests, which often involve hijacking buses and delivery trucks.

In March, protesters allied with the college seized a small truck and used it to break the wooden doors of the National Palace in Mexico City.

They knocked on the doors and entered the colonial-era palace, where the president lives and holds his daily press conferences, before being removed by security guards. The palace is a historic building dating back to the eighteenth century and was built on the site of the Aztec emperors' palace.

The demonstration was called, like many others over the years, to protest the kidnapping and killing of 43 students a decade ago, and the mass disappearance remains one of the most famous human rights cases in Mexico.

In 2014, a group of students was attacked by municipal police in the southern Guerrero city of Iguala, where they were handed over to a local drug gang that killed them and apparently burned their bodies. Since the September 26 attack, only three of their remains have been identified.

After initial cover-up, last year the government's truth commission concluded that local, state, and federal authorities colluded with the gang to kill the students in what it called a "state crime."

The rural radical teachers' colleges, which suffer from underfunding in Mexico, have a tradition spanning decades of violent protests. In fact, when they were kidnapped, the students themselves were hijacking passenger buses they would use to travel to another protest.