At least four persons were killed while two others were injured in a US drone strike launched Friday afternoon at South Waziristan Agency. A private television channel quoted officials sources as saying that the US drones fired two missiles at a house suspected of militants' hideout in the Tehsil Bermal area of South Waziristan . As a result, four persons were killed while two others were injured. Friday afternoon's U.S. drone strike is the 48th of its kind in Pakistan in 2011. To date, a total of 439 people have reportedly been killed in such strikes.