PESHAWAR - At least four suspected persons were killed and reportedly three others injured in a drone attack in South Waziristan Agency on Thursday afternoon.According to details, US drone fired three missiles which targeted a house in the Barmal area, which is the main town of the SWA. The sources said that it is believed that foreigners may have been killed in the strike.They said that the drone attack was targeted a house, resulting in the death of four suspected persons. Agencies add: Local security officials, giving a different account of the strike, said the missiles fired by the US drone landed at open fields in Sheen Warsak and caused no damage or casualties.It is highly unusual for no casualties to be reported when unmanned American aircraft target suspected Taliban and Al-Qaeda-linked militants in semi-autonomous tribal belt.