Thick smoke rises from the Westgate Shopping Centre in Nairobi following a string of explosions during the third day of a stand-off between Kenyan security forces and gunmen inside the building in Nairobi, Kenya, Sept. 23, 2013. Kenyan security forces on Monday stepped up their onslaught against Al-Qaida allied Al-Shabaab gunmen to end a siege on the mall and free hostages. [Photo/Xinhua]