By Dialogo August 23, 2010 Thirteen presumed leftist guerrillas were killed when air force planes dropped bombs on the suspects in rural northwestern Colombia, officials said on August 19. The offensive in Antioquia province against the National Liberation Army (ELN) included work by police intelligence, the army and air force, officials said. After the bombing soldiers, Marines and police entered the bombed site and found bodies, supplies and weapons, including eight automatic rifles, officials said. The ELN is Colombia’s second-largest rebel force, with 2,500 fighters at arms. The initial toll given after the bombing on August 18 had been seven. The Revolutionary Armed Forces of Colombia (FARC) are the country’s oldest and largest insurgency, fighting since the 1960s. They have between 6,500-10,000 fighters, according to different estimates. Both leftist groups, as well as right-wing paramilitary groups, have been linked to drug trafficking.