CLASHES between Mexican federal police and protesters who were organising a concert in solidarity with 43 missing college students left at least 21 people injured and several cars in flames in the southern state of Guerrero on Sunday.

Eight officers were injured, including five who were run over by a vehicle. Three others were allegedly beaten by protesting teachers, leaving one officer with “severe brain damage,” according to a police spokesman.

The Tlachinollan human rights group, which supports the relatives of the missing students, said that the violence had left at least 13 people injured, including students, teachers, parents of several of the missing students and two journalists.

Each side blamed the other for initiating the clash in Chilpancingo, the capital of Guerrero state.

The fighting began early on Sunday when students from the Ayotzinapa teachers college put up metal barriers in preparation for the concert, blocking the street that led to the hotel where federal police were staying.

The case of the missing students, who disappeared in September after being in the hands of corrupt local government officials linked to a drug cartel, has ignited protests across Mexico.

Mexico’s attorney general said today that 80 people had been arrested so far in the case, including 44 police officers from the cities of Iguala and Cocula.

Former Iguala mayor Jose Luis Abarca has also been arrested. He is under investigation for ordering the September 26 attacks.

So far, the body of one student has been positively identified.