The four men are seen walking casually, holding machine guns.
Closed-circuit television footage from Nairobi's Westgate Mall shows four attackers, walking calmly through a storeroom inside the shopping complex. The footage broadcast by local Citizen TV also shows that one of the gunmen has blood on his lower pant leg.
Officials originally said up to 15 attackers took part in the four-day siege which began Sept. 21. The footage released late on Friday indicates that there could have been far fewer.
The four men are seen walking casually, holding machine guns. One of the men's pant legs appears to be stained with blood but it is unclear if the blood is his, or that of his victims.