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

A police official said eight officers were injured, including five who were run over by a vehicle. Three others were said to have been beaten by protesting teachers, leaving one officer with “severe brain damage”. The official was not authorised to talk to the press and spoke on condition of anonymity.

The Tlachinollan human rights group, which supports the relatives of the missing students, said the violence left at least 13 people injured, including students, teachers, parents of the missing students and two journalists, including a photographer who was working with Associated Press.

Each side blamed the other for initiating the clash in Chilpancingo, the capital of Guerrero state. It began early on Sunday when students from the Ayotzinapa teachers’ college began blocking a street with metal barriers in preparation for the concert. The blocked street led to the hotel where federal police were staying.

The case of the missing students, who disappeared in September after being attacked by police, has ignited protests across Mexico.

Mexico’s attorney general said 80 people had been arrested so far in the case, including 44 police officers from the cities of Iguala and Cocula and former Iguala mayor Jose Luis Abarca, who is under investigation after being accused of ordering the 26 September attacks.

So far, one dead student has been positively identified.