Kenya said its security forces were in control of the Nairobi shopping mall where Islamist fighters killed at least 62 people, and police were doing a final sweep of shops early on Tuesday after rescuing the last hostages.
An overnight silence outside the large, upmarket Westgate mall was broken at daybreak with a loud burst of gunfire from inside, suggesting the complex had not yet been fully secured. A lone military chopper circled above.
"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 10 and 15 militants stormed the mall, which with its rich clientele epitomised the African consumer bonanza that is drawing foreign investment to one of the world's fastest growing regions.
Foreign Minister Amina Mohamed said in a U.S. television interview that "two or three Americans" and a British woman were among the militants who led the attack, launched on Saturday and claimed by Somalia's al Qaeda-linked al Shabaab group.
Mohamed told the "PBS Newshour" show the Americans were "young men, about between maybe 18 and 19" years old. They were of Somali origin or Arab origin, and had lived in the U.S., "in Minnesota and one other place", she said.
U.S. 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, U.S. security sources said.
"We do monitor very carefully and have for some time been concerned about efforts by al Shabaab to recruit Americans or U.S. persons to come to Somalia," White House deputy national security adviser Ben Rhodes said.
He told reporters travelling with U.S. President Barack Obama to the United Nations in New York that he had no direct information that Americans had participated in the attack.
Obama offered U.S. support, saying he believed Kenya - the scene of one of al Qaeda's first major attacks, in 1998, and a neighbour of chaotic Somalia - would continue to be a regional pillar of stability.
Obama, whose father was born in Kenya, said the United States stood with Kenyans against "this terrible outrage."
Kenyan officials have tried to reassure the country that it would seize control of the situation.
"We appeal for patience, keep calm, avoid Westgate at all costs and wait for the official communication," the Ministry of Interior and Coordination of National Government in The Office of the President said on Twitter.
A press briefing was expected later on Tuesday.
Al Qaeda killed more than 200 people when it bombed the U.S. Embassy in Nairobi in 1998. When fighters from its Somali ideological counterpart stormed the mall on Saturday, they hit a high-profile symbol of Kenya's economic power.
Kenya has sent troops to Somalia as part of an African Union force trying to stabilise the country, which was long without a functioning government, and push back al Shabaab.
It has also suffered internal instability. President Uhuru Kenyatta, who lost a nephew in the weekend bloodbath, faces charges of crimes against humanity at the International Criminal Court for his alleged role in coordinating violence after disputed elections in 2007. He denies the charges.
Kenyatta has dismissed a demand that he pull Kenyan forces out of Somalia, saying he would not relent in a "war on terror."
British Defence Secretary Philip Hammond said he believed six Britons had died in the attack. Other known foreign victims are from China, Ghana, France, the Netherlands and Canada. Kenyan officials said the total death toll was at least 62.
Speculation rose about the identity of the attackers. Interior Minister Joseph Ole Lenku had earlier said they were all men but that some had dressed as women.
Despite his comments, one intelligence officer and two soldiers told Reuters that one of the dead militants was a white woman, likely to fuel speculation that she is the wanted widow of one of the suicide bombers who together killed more than 50 people on London's transport system in 2005.
Called the "white widow" by the British press, Samantha Lewthwaite is wanted in connection with an alleged plot to attack hotels and restaurants in Kenya. Asked if the dead woman was Lewthwaite, the intelligence officer said: "We don't know."
From Mali to Algeria, Nigeria to Kenya, violent Islamist groups - tapping into local poverty, conflict, inequality or exclusion but espousing a similar anti-Western, anti-Christian creed - are striking at state authority and international interests, both economic and political.
John Campbell, a former U.S. ambassador to Nigeria, said he believed insurgents such as those who rebelled in Mali last year, the Nigerian Boko Haram Islamist sect and the Nairobi mall raiders were also partly motivated by anger with what he called "pervasive malgovernance" in Africa.
"This is undoubtedly anti-Western and anti-Christian but it also taps into a lot of deep popular anger against the political economy in which they find themselves, in which a very small group of people are basically raking off the wealth," he said.