CNN Exclusive: Chilling video of mall siege in Nairobi

CNN has obtained exclusive closed-circuit television footage of the Westgate Mall attack in Nairobi, Kenya. The footage was taken on September 21, day one of the four-day siege. The attack left at least 67 people dead, many more injured and dozens unaccounted for.

CNN’s Nima Elbagir (@NimaCNN), who reviewed hours of this footage, reports the attackers took turns praying and chatting on their cell phones while spraying bullets at terrified shoppers.