Kenyan special forces were still fighting on Tuesday morning what sources said were “one or two” Islamist militants inside the Westgate shopping mall in Nairobi.
As sporadic gunfire and an explosion were heard at dawn, the attackers were said to be isolated either inside or next to a casino on one of the upper floors.
Earlier Kenya’s interior ministry said its forces were in control of the centre and that all hostages had been freed.
The government says the militants include several foreigners.
“(There are) two or three Americans and I think so far I have heard of one Brit… a woman, and I think she has done this many times before,” Kenyan Foreign Minister Amina Mohamed told an interviewer from the US TV programme PBS Newshour.
“The Americans, from the information that we have are young men: between 18 and 19, of Somali origin or Arab origin, but who lived in the US,” she added.
Officials have said that three militants have been killed. The operation against armed militants has now lasted three nights.
At least 62 people died and 175 were injured after fighters, thought to be members of Somalia’s al-Shabaab movement, stormed the shopping complex on Saturday.