RESIDENTS of Cebu, Bohol, Samar and Leyte islands experienced a massive blackout early Thursday, prompting the Department of Energy and the National Grid Corporation of the Philippines (NGCP) to launch an investigation to find what went wrong. Initially, the Visayan Electrical Company (VECO), which services Cebu Island, reported a loss of 98 megawatts for yet unknown reasons. Electicity was restored at about 9 a.m., when other plants were required to produce enough power. The NGCP also suspects that the blackout may have been caused by one of the malfunctioning power plants in Samar island. Power in Cebu, Bohol, Samar and Leyte are interconnected by a grid.