Kenyan security forces are combing the Nairobi shopping centre attacked by suspected al-Shabab militants, as they seek to secure the site.
An explosion and bursts of gunfire were heard coming from the Westgate complex on Tuesday morning, as speculation grew that the operation was nearing its end.
At least 62 people have been killed and more than 170 injured.
Meanwhile, Kenya's foreign minister said "two or three" Americans and a British woman were among the attackers.
In an interview with the US TV programme PBS Newshour, Amina Mohamed said the Americans were 18 or 19 years old, of Somali or Arab origin, and lived "in Minnesota and one other place".
She said the Briton was a woman who had "done this many times before".
Ms Mohamed appeared to contradict earlier comments from Kenya's interior minister, who suggested that all the attackers were men - though some may have been dressed as women....PICTURES AND MORE HERE
ALL HOSTAGES FREED.
Kenya has said its security forces are in control of the Nairobi shopping mall where Islamist fighters killed at least 62 people, and police are doing a final sweep of shops early after rescuing the last hostages.
However an overnight silence outside the Westgate mall was broken at daybreak on Tuesday with a loud burst of gunfire from inside, suggesting the complex had not yet been fully secured.
"Our forces are combing the mall floor by floor looking for anyone left behind. We believe all hostages have been released," the Ministry of Interior said on Twitter early on Tuesday, adding his forces were "in control" of the building.
A trickle of survivors left on Monday, but the fate of the missing was unclear, four days after a group of between ten and 15 militants stormed the mall.
US authorities are urgently looking into information from the Kenyan government that residents of Western countries, including the United States, may have been among the militants.
SOURCE: ITN news