PESHAWAR Six persons were killed and four others sustained critical injuries when a US drone targeted a house in Boyan village of Data Khail tehsil in NWA on Wednesday evening. Sources informed that the unmanned aircraft fired two missiles at a suspected hideout of militants. The injured were shifted to Agency Headquarter Hospital, Miranshah. So far neither the US-led allied forces nor the Pakistani authorities have confirmed the attack. Reuters adds: A suspected US drone aircraft fired two missiles into North Waziristan region on Tuesday, killing six militants, intelligence officials said. The United States has stepped up its attacks by pilotless drones in Pakistan since a suicide bomber killed seven Central Intelligence Agency (CIA) operatives at a US base in eastern Afghanistan on Dec 30. The latest drone strike targeted a house in a village in the Datta Khel district, 35 km west of Miranshah, the main town in North Waziristan, a region known as a hotbed of Taliban and al Qaeda militants. One missile hit a compound and the other hit a vehicle outside it. Six militants were killed, an official said. The death toll had initially been put at three. Last Thursday, a US drone targeted Taliban leader Hakimullah Mehsud in the South Waziristan region on the Afghan border but it was not known if he was among 12 militants killed. The Taliban later issued an audiotape purportedly from Mehsud, denying he had been killed. Mehsud appeared in a farewell video sitting beside the bomber, a double agent, who killed the seven CIA operatives. The video was released 10 days after the brazen strike. The video created the impression his Taliban movement had helped organise the attack. Most of the recent US missile strikes have been in North Waziristan, opposite the eastern Afghan province where the CIA agents were attacked, and a bastion of an al Qaeda-linked Afghan Taliban faction known as the Haqqani network.