Saboteurs blew up a junction where multiple oil pipelines cross the Tigris River in northern Iraq on Tuesday, setting off a chain reaction in power generation systems that left the entire country without power, officials said. Firefighters struggled to put out the blaze after the attack near Beiji, 250 kilometers (155 miles) north of Baghdad. Crude oil cascaded down the hillside into the river. Fire burned atop the water, fueled by the gushing oil. Beiji is the point where several oil pipelines converge, said Lt. Col. Lee Morrison of the U.S. Army Corps of Engineers. One of them apparently was a domestic pipeline that fed a local power plant. The explosion set off a fire that melted cables and led to the power outage, electricity officials said. "Beiji is the chokepoint," Morrison said. "It's so easy to hit." The 3 a.m. attack came soon after engineers had completed a two-month project to install two critical valves that had been damaged in an earlier blast.