QUETTA: Unidentified persons on Monday fired eight rockets at security force check posts, while four people, including one Frontier Corps officer, sustained serious injuries when a landmine exploded in Dera Bugti district, sources said. Sources told Daily Times that unknown assailants had fired eight rockets at the FC Bhadur check post in Kohlu district, before firing indiscriminately against officers. There were no reports of FC casualties. In a separate incident, four people, including a FC officer, sustained serious injuries when a landmine exploded in the Sangsila locality of Dera Bugti district.