Hangu (Pakistan), May 23 : At least four Frontier Constabulary (FC) personnel and two private security guards were martyred when a gas plant in Tall tehsil of Hangu district of Khyber Pakhtunkhwa province in Pakistan came under terrorist attack, media reports said. Tall's Deputy Superintendent of Police said that heavily-armed militants struck the private gas extraction plant in the mountainous region, Geo News reported. He also said that the militants have also damaged a solar power plant at the affected plant before fleeing to the adjoining North Waziristan area, where they had come from. He said that a joint search operation was underway in the area, The News reported. The security personnel fought bravely for two hours and repulsed the attack, the police official added. A large number of police are standing guard at the gas plant after the terror attack. Various militant factions, including the banned Tehreek-e-Taliban Pakistan (TTP), have operated out of remote mountains in the northwest for years, launching attacks on the security forces and infrastructure in their campaign against the state, The News reported. /IANS