HANGU - At least four policemen were injured and their van damaged partially when a rocket went off accidentally here on Saturday. According to details, escorted by the personnel of Elite Police Force, a convoy of private oil exploration company 'MoL was on its way to Kotkai area in Hangu district. However, instead of stopping at a speed breaker near a police check post on Tal Road, a speedy police mobile van bearing number, Swat B 1377, sprint over the breaker. Due to which, a police constable Sharif Ullah fell down from the vehicle and a rocket launcher he was holding in his hand went off unintentionally and hit another police mobile coming in the same direction, which resulted in injuring four other policemen.