Gunfire was heard after the Kenyan government said it was in control of the Westgate shopping mall in Nairobi. A government statement had earlier said it was believed that all hostages taken by gunman had been released.
Kenya's Interior Ministry said early on Tuesday that it had secured the mall that was attacked by Islamist militants in Nairobi.
"We are in control of Westgate," the ministry said on its Twitter account, some 60 hours after the siege of the fashionable shopping mall began. Smoke, which authorities attribute to a fire started by the gunmen themselves, continued to billow from the scene.
However, by about 6.30 a.m.local time, Kenyan troops were reported to be fighting one or two gunmen in a final push, with hopes that hostages might still be rescued.
Before the latest rounds of fire were heard, one government spokesman had been reported by the AFP news agency as saying that the three-day-long siege, in which the attackers killed at least 62 shoppers and staff, was near to being declared over.
"Our special forces are inside the building checking the rooms. We think that everyone, the hostages, have been evacuated, but we don't want to take any chances," Manoah Esipisu told the agency.
"The special forces call this sanitizing. At the moment they have not met any resistance, but of course we are not ruling out the possibility that there are a couple of them hiding in a remote room or corner."
International list of victims
Both Kenyans and foreigners were confirmed dead in the attack, with British, Australian, French, Indian, Canadian, Dutch, Ghanaian and Chinese citizens reported among those killed. Officials said the death toll could rise after security forces have completely searched the complex.
The al Shabab militant group, based in neighboring Somalia, claimed responsibility for the raid on Saturday. Al Shabab said the action was in reprisal for Kenya's military intervention in Somalia, where Kenyan troops are deployed alongside those from Ehtiopia and African Union peacekeeping forces (AMISOM) to fight the Islamist insurgency.
Kenyan President Uhuru Kenyatta, who lost a nephew in the violence on Saturday, called the attack "despicable and beastly."
As the raid entered its fourth day, US president Barack Obama condemned the killing and offered Washington's support to Kenya. "We stand with them against this terrible outrage that's occurred. We will provide them with whatever law enforcement support that is necessary. And we are confident that Kenya will continue to be a pillar of stability in Eastern Africa."
UN chief Ban Ki-moon said the violence was "totally reprehensible".
On Monday, the International Criminal Court suspended the atrocities trial of Kenya's vice president, William Ruto, for one week while the country deals with the hostage situation.
rc/jr (AFP, AP, dpa, Reuters)