Guatemala City: In the March 2015 attack, members of a gang called Barrio 18 threw a fragmentation grenade at prison guards escorting an inmate from a rival gang to a hospital outside Guatemala City for a medical appointment.
That inmate and the guards escaped injury. But two other people heading to the hospital died on the spot, and four others died days later from injuries sustained in the blast.
Police say the people arrested yesterday are wanted in connection with three other killings ordered by jailed gang leaders.
Guatemala, El Salvador and Honduras are struggling to cope with rampant violence from powerful street gangs. Deadly turf battles between the gangs are common.