The African Union and United Nations vowed Tuesday to step up the fight against al-Qaida-linked Shebab militants in Somalia following the deadly siege in Kenya now in its fourth day.

"Our resolve is to fight now more than ever before," the deputy head of the AU's executive branch, Erastus Mwencha, told Agence France Presse.

One of the Islamist attackers besieging a Nairobi shopping mall handed chocolate to a four-year-old British boy caught up in the crisis and asked for forgiveness, his uncle told a newspaper on Tuesday.

Four-year-old Elliott Prior, who had been shopping with his mother and sister at the Westgate mall when it came under attack on Saturday, confronted one of the militants, telling him "you're a very bad man," his uncle told The Sun.

Kenyan troops are in "control" of Nairobi's Westgate shopping mall three days after a deadly siege by Islamists, who, according to Kenya's foreign minister, include "two to three Americans" and a British woman.

As the interior ministry said early Tuesday that all hostages trapped by the militants are believed to have been freed, Kenyan Foreign Minister Amina Mohamed underlined the global scope of the attack.

U.S. President Barack Obama spoke to his Kenyan counterpart Monday and promised him "whatever law enforcement support is necessary" in the wake of an attack on Nairobi shoppers.

Obama's father was Kenyan, but the U.S. leader has largely kept his distance from President Uhuru Kenyatta, who has been named a suspect in an International Criminal Court probe of Kenyan electoral violence.

Six Britons are now believed to have been killed in an attack at a Nairobi shopping mall staged by Islamist militants, Defense Secretary Philip Hammond said on Monday.

"Our current best estimate is we now have six British nationals who have died in this incident," he said after a meeting of the government's emergency committee chaired by Prime Minister David Cameron.

The United States is monitoring the bloody siege in a Kenyan shopping mall and will stand with the country's people in the days ahead, U.S. Secretary of State John Kerry said Monday.

"Ruthless and valueless terrorists remain a serious challenge everywhere in the world as we all know, whether it's in downtown Manhattan or in a mall in Nairobi, or anywhere else in the world," Kerry said in remarks to a conference at the United Nations.

The bodies are laid out on metal blocks, victims from all walks of life lying side by side amid a stench of death in Nairobi City Mortuary.

Vehicles drove in and out, from shiny black hearses to beat-up minibuses, to fetch the dead from the attack by Somali militants on an upmarket Nairobi shopping mall.

Nairobi's Westgate mall, with its designer shops and restaurants, has become a symbol of Kenya's rising prosperity. On Saturday, September 21, it became the scene of one of the most chilling attacks in East Africa's history, claiming the lives of at least 69 people.

Nairobi-based AFPTV journalist Nichole Sobecki was the only television journalist able to gain access to the Westgate mall, just after the attack started. Following is her account of the horrific events:

The International Criminal Court on Monday excused Kenyan Vice President William Ruto from his crimes against humanity trial for a week so he can deal with the Nairobi militant attack.

"In the light of the circumstances... the Chamber does excuse Mr Ruto from the proceedings before the court... for one week only," Judge Chile Eboe-Osuji said at an urgent hearing.

Kenyan security forces were locked in a fierce, final battle with Somali Islamist gunmen inside an upmarket Nairobi shopping mall on Monday as huge explosions and a barrage of heavy gunfire echoed out of the complex.

Thick black smoke billowed for several hours from the Westgate mall as Kenyan officials said the more than two-day-long siege -- in which the gunmen have massacred at least 62 people and taken dozens more hostage -- was close to being resolved.