NAIROBI, Kenya — The bloody standoff at a Kenyan shopping mall edged closer to a conclusion Monday night, with Kenyan officials saying that their troops were securing the building and that there were no more civilians trapped inside.
"We're in control of Westgate," Kenya's Interior Ministry said in a Twitter message late Monday night, referring to the large, upscale mall that Islamist militants stormed on Saturday, killing at least 62 people.
Among the militants were two or three young U.S. men who appeared to be of Somali or Arab origin, Kenya's foreign minister, Amina Mohamed, said Monday. In an interview on PBS, Mohamed said the U.S. attackers were originally from Minnesota or Missouri. "That just goes to underline the global nature of the war that we're fighting," she said.
The State Department's senior spokeswoman, Jen Psaki, said: "We have no definitive evidence of the nationalities or identities of the perpetrators at this time. We will continue to look into these reports."
For more than two days, Kenyan forces have struggled to vanquish the militants, who, after slaughtering shoppers, holed up in various corners of the mall with military-grade weaponry. Hundreds of elite Kenyan troops — backed by armored personnel carriers, helicopters, planes and security officials from Israel, France, Britain and the U.S. — have been deployed, but the militants, estimated to number from 10 to 15, refused to surrender.
By late Monday night, the sound of gunfire had tapered off and Kenyan news media reported that all the militants had been killed.
"We believe all hostages have been released," said the Kenya National Disaster Operation Center in a Twitter message. "Special forces and KDF soldiers combing the building. Situation of hostiles to be confirmed."
Kenyan officials have repeatedly tried to reassure the country — and the world — that they are bringing the crisis under control, mindful of the damage to the nation's image as a cornerstone of stability in an often turbulent region.
Kenya is a crucial U.S. partner, whose security forces work closely with their Western counterparts to contain Islamist militants in the region. Now Kenya's capital, considered an oasis of prosperity in this part of Africa and an important base for Western embassies and businesses, has become a battleground in the conflict, and there is growing concern that this attack will not be the last.
Some of the ringleaders of the assault — in which masked gunmen moved methodically through the crowded mall Saturday, killing men, women and children — may have escaped during the initial confusion, the New York Times reported, citing several witnesses. One witness said that an assailant quickly tore off his clothes and changed into a new outfit before running out, hands raised, blending in with a crowd of fleeing civilians.
Security officials in Nairobi said that two other militants — both women who appeared to be directing other assailants during the killings — also managed to escape after the initial stage of the attack, raising fears that well-trained terrorists could be on the loose in Nairobi. Several witnesses have said that some of the militants were clearly not African and may have been from Western countries, but U.S. officials said they could not confirm that.
On Monday afternoon, Kenyan security officials acknowledged that the effort to end the standoff had taken longer than expected, though they offered a different account of their setbacks, saying that about 10 Kenyan soldiers had been injured but none killed.
Al-Shabab, a brutal Somali extremist group, claimed responsibility for the siege on the mall. Its spokesmen said that the attack was revenge for Kenya's military incursion into Somalia, which began in 2011, when Kenya sent thousands of troops across the border to push back al-Shabab.
Three years ago, the group also claimed credit for the coordinated bombings that killed more than 70 people in Uganda as crowds gathered to watch the World Cup, calling it retribution for Uganda's decision to send troops to Somalia as part of the African Union's effort to stabilize the country.
But the possible presence of militants from outside of Africa in the mall attack — and the way the assailants fended off attempts to dislodge them — has raised questions about al-Shabab's latest claims. Some Western security officials are now beginning to wonder if other terrorist groups may be involved.
"They are clearly a multinational collection from all over the world," said Julius Karangi, chief of the Kenyan general staff. "We are fighting global terrorism here."
President Obama said Monday that the United States stood with Kenya's leadership "against this terrible outrage that's occurred."
The U.S. government is contributing "technical support and some equipment to assist Kenyan security forces" in responding to the attack, the Washington Post reported, citing an unnamed State Department official. The department said American military personnel based at the U.S. Embassy in Nairobi have been helping the Kenyans.