Kenya's Interior Minister Joseph Ole Lenku said the evacuation of hostages had gone "very, very well" and that Kenyan officials were "very certain" that few if any hostages were left in the building.
But with the mall cordoned off and under heavy security it was not possible to independently verify the assertions.
Westgate mall, a vast complex with multiple banks that have secure vaults and bulletproof glass partitions, as well as a casino, is difficult to take, the official said.