They concentrated on both civilian and military targets, knocking out bridges, closing major roads, attacking convoys, disrupting the electric power system and industrial production, and attacking police stations and Soviet military installations and air bases. They assassinated government officials and PDPA members, and laid siege to small rural outposts. In March 1982, a bomb exploded at the Ministry of Education, damaging several buildings. In the same month, a widespread power failure darkened Kabul when a pylon on the transmission line from the Naghlu power station was blown up. In June 1982 a column of about 1,000 young communist party members sent out to work in the Panjshir valley were ambushed within 30 km of Kabul, with heavy loss of life. On September 4, 1985, insurgents shot down a domestic Bakhtar Airlines plane as it took off from Kandahar airport, killing all 52 people aboard.