Suspected rebels dynamited four energy pylons Monday, leaving more than 2.3 million people in southwestern Colombia without electricity. Energy officials were scrambling to find a temporary fix while the army secured the area so crews could repair the downed towers, Mines and Energy Minister Luis Ernesto Mejia said. Authorities believe Colombia's main rebel group, the Revolutionary Armed Forces of Colombia, or FARC, was responsible, an army official said.The FARC and a smaller guerrilla group have been fighting the Colombian government for four decades. They often blow up energy towers, bridges, oil pipelines and other infrastructure, aiming to wreak havoc on the economy. The rebels have de-facto control of large parts of the region along the Ecuadorean border where the pylon attacks occurred and in the past few months have launched several deadly assaults on military installations in the area.