QUITO, Ecuador — Rival gangs of inmates fought in two prisons in Ecuador, killing at least 18 people and injuring dozens, authorities said Thursday.

Violence broke out on Wednesday in the main prison in the city of Guayaquil as well as the Latacunga prison in central Ecuador, according to prison authorities.

Nine police officers and 35 prisoners were injured in the fighting. Police have regained control of the prisons.

Police said on Twitter that there had been an escape attempt at the Latacunga prison, but that 45 prisoners were recaptured.

In June, a fight between gangs in a prison in Ecuador killed two people and injured 11. In February, fighting in Ecuadorian prisons killed about 80 prisoners.