The retired head of Pakistan's elite army commando unit was shot dead Wednesday by unidentified gunmen near his house in the capital city of Islamabad, police said. The motive behind the killing of Major General Amir Faisal Alvi -- who retired two years ago as chief commander of the army's Special Services Group targeting Islamic militants -- was not immediately clear. "General Alvi left his house in his car when gunmen on a motorbike and in a Pajero (SUV) sprayed bullets at him near his house," local area police officer Sajid Ahmed said. Pakistan is reeling under spiralling violence blamed on Al-Qaeda and Taliban militants based in the tribal territory bordering Afghanistan. Alvi commanded the Special Services Group in its covert operations against militants in the tribal regions.