At least 28 prisoners were killed in a riot between the suspected members of rival gangs in a prison in Mexican state of Guerrero, officials said. Guerrero government on Thursday updated the toll from original five to 28 as police searched the prison. Three other prisoners sustained mild injuries, Xinhua news agency reported.

At a press conference, Guerrero’s security spokesperson, Roberto Alvarez Heredia, said that the fight began around 4 AM in Las Cruces prison in Acupalco.

The prison, where the riot broke out, is the most crowded in Guerrero, with 2,100 prisoners, according to Mexican government statistics.