SWABI - Unidentified militants targeted the transmission line from Tarbela Dam to Peshawar with explosive materials at night, however, it remained unharmed, said the police here on Wednesday. Three of the four explosive materials planted to a pylon went off at midnight, however the fourth explosive device did not explode due to unknown reasons. It helped the transmission line survive the onslaught, they said. The targeted area was Marghuz and in the same region incidents of similar nature had already occurred many times.  The unexploded materials defused by the bomb disposal squad later on. The explosions awakened the people and the police reached to the area of Marghuz immediately. They collected the information. Meanwhile, it has been learnt that the Wapda authorities have been working on the repairing of the pylon and officers in Tarbela Dam told this correspondent that they hope that it would completed very soon.