QUITO, July 22 (Reuters) - At least 18 inmates died and several police were injured during riots at two of Ecuador"s largest penitentiaries, the Andean country"s SNAI prison authority said late on Wednesday, marking the second major deadly wave of prison violence this year. Special police units deployed to the jails in southern Guayas province, home to the largest city of Guayaquil, and Cotopaxi province, south of capital Quito, to quell the violence. In February, at least 79 inmates died at three prisons - including the centers in Guayas and Cotopaxi - in clashes between rival gangs. On Thursday, Ecuador"s police service wrote on Twitter that 45 inmates were captured as they attempted to escape from the Cotopaxi prison, where SNAI said 10 inmates died and 35 were injured. Eight prisoners died at the Guayas jail, according to SNAI. Ecuadorian officials have for years sought to reduce violence at the country"s overcrowded prisons, home to some 38,000 inmates.