Sounds of heavy gunfire erupted from Nairobi's Westgate mall Tuesday, even as authorities said for the second day that they had the building under their control.

The mall "is under the full control of govt forces and we are carrying out a sweep to ensure its safe for everyone," Kenyan police tweeted Tuesday. Kenya's Interior Ministry also gave reason for hope: "We're very near the end."

But four days after Al-Shabaab terrorists stormed the swanky mall, killing 62 people, several gunmen — including snipers — were still inside, two senior officials said. And it's uncertain how many hostages might still be trapped, although Kenyan officials tweeted early Tuesday that they believed all of them had been freed.