The mastermind behind Pakistan's 2014 school massacre in Peshawar which claimed at least 150 lives was killed in a US drone attack in Afghanistan, officials said Tuesday.Umar Naray, also known as Khalifa Umar Mansoor, was targeted along with three associates on Saturday in Nangarhar province."We have intercepted a communication which shows that Umar Naray was killed in the drone strike," a Pakistani intelligence official said on condition of anonymity.A US official in Kabul confirmed the airstrike."I can confirm that an airstrike was conducted against a Taliban position in Nangarhar on Saturday. However, we are not permitted to share the details of the airstrike," said Captain Andrea Dykes.The drone strike targeted the hideout of Pakistani militants in Afghanistan, another Pakistani official said. A militant commander would not comment on the reported drone attack or on reports of Naray's death."We will issue a statement once we are in position to confirm or reject the report of his death," the commander said.Naray masterminded the attack on a school in the north-western city Peshawar on December 16, 2014, which killed at least 150 people, mostly schoolchildren.He also claimed responsibility for the attack at Bacha Khan University in Charsadda town in January, which killed at least 21.Naray was the chief of the Geedar group of militants, which is active in the provincial capital Peshawar and adjacent areas.Many of the group's militants fled to Afghanistan after the Pakistan army launched a major operation in 2014.