Members of a violent Central American gang on Tuesday claimed they routinely pay prison officers to provide them with weapons, and they blamed a rival group for starting coordinated riots at seven prisons that left 35 inmates dead.

Interviewed as they recovered from gunshot and stab wounds, members of the Mara 18 blamed Monday's near-simultaneous uprisings at Guatemalan prisons on the rival Mara Salvatrucha gang. Gangs are known as "maras" in Central America.

Herman Ivan Aguirra, 19, a two-year member of the Mara 18 gang from Guatemala City, said he and other prisoners were exercising when Mara Salvatrucha members seemingly came out of nowhere wielding knives, guns and grenades.

Monday's violence began with two grenade explosions at a prison for gang members known as El Hoyon in Escuintla, officials said.

It was followed by coordinated attacks by Mara Salvatrucha gang members against the Mara 18 gang at six other prisons, they said. Most of the injured belonged to Mara 18, according to local media.

Mara 18 gang members recovering at the Escuintla Hospital said the two gangs are always fighting each other and that officers help them by providing them with weapons in exchange for bribes.

Officials did not respond immediately to the allegations. Interior Minister Carlos Vielmann said earlier Tuesday that prison visitors smuggled in guns and passed along messages to inmates in other facilities, while some of the prisoners used cell phones to help launch the riots.

Vielmann said Monday's attacks showed the organizational power of the gangs, which have spread terror throughout much of the region, prompting harsh official crackdowns.

More than a dozen police officers kept watch over the 15 prisoners who remained on the Escuintla Hospital's second floor Tuesday. Some of the gang members were handcuffed to their gurneys and shouted obscenities at visitors.