A Pakistani rescuer displays a bottle of military style red smoke found at a bomb blast site in Peshawar, Pakistan, on September 3, 2012. Four people including two Americans were killed in a suicide bomb attack on a car of American consulate in the northwestern city of Peshawar on Monday. [Xinhua]

Pakistani rescuers inspect a destroyed vehicle at a bomb blast site in Peshawar, Pakistan, on September 3, 2012. Four people including two Americans were killed in a suicide bomb attack on a car of American consulate in the northwestern city of Peshawar on Monday. [Xinhua]

A Pakistani rescuer displays a burnt US passport found at a bomb blast site in Peshawar, Pakistan, on September 3, 2012. Four people including two Americans were killed in a suicide bomb attack on a car of American consulate in the northwestern city of Peshawar on Monday. [Xinhua]

Pakistani hospital staff treat a person injured in a bomb blast site in Peshawar, Pakistan, on September 3, 2012. Four people including two Americans were killed in a suicide bomb attack on a car of American consulate in the northwestern city of Peshawar on Monday. [Xinhua]