NAIROBI, Kenya - Hostages are being held alive inside an upscale Nairobi mall and the militant fighters who attacked the building are "still holding their ground" against government forces trying to end the siege, the Islamic extremist group said Tuesday.
In a new Twitter feed established Tuesday after previous ones were cut off, the the al-Qaida-linked rebel group al-Shabab said the attack that began Saturday and has claimed more than 60 lives so far was "far greater than how the Kenyans perceive it."
"There are countless number of dead bodies still scattered inside the mall, and the mujahideen are still holding their ground," the group claimed.
It added that the hostages are "still alive looking quite disconcerted but, nevertheless, alive."
The Kenyan police responded with a Twitter message of its own, urging people to ignore "enemy... propaganda" and assuring that the defense forces were continuing to "neutralize" the terrorist threat.
"Troops now in mop up operations in the building," the police said. "More to follow. Be calm."
Authorities have said they are involved in a final push to clear out the remaining attackers. But authorities have before referred to their operations as final. And despite the Kenyan government assurances of success, an explosion and gunfire could be heard coming from the mall at around 6:30 a.m., followed by the sustained chatter of automatic weapons for about a minute almost three hours later, according to Associated Press reporters at the scene.
Security forces carried a body out of the mall, which remained on fire, with flames and smoke visible. A Kenyan soldier wearing bomb disposal protective gear also exited the building.
While the government announced Sunday that "most" hostages had been released, a security expert with contacts inside the mall said at least 10 were still being held by a band of attackers described as "a multinational collection from all over the world."
Kenyan Foreign Minister Amina Mohamed said "two or three Americans" and "one Brit" were among those who attacked the mall.
She said in an interview with the PBS "NewsHour" program that the Americans were 18 to 19 years old, of Somali or Arab origin and lived "in Minnesota and one other place" in the U.S. The attacker from Britain was a woman who has "done this many times before," Mohamed said.
U.S. officials said they were looking into whether any Americans were involved. State Department spokeswoman Jen Psaki said Monday that the department had "no definitive evidence of the nationalities or the identities" of the attackers.
Britain's foreign office said it was aware of the foreign minister's remarks, but would not confirm if a British woman was involved.
The security expert, who insisted on anonymity to talk freely about the situation, said many hostages had been freed or escaped in the previous 24-36 hours, including some who were in hiding.
However, there were at least 30 hostages when the assault by al-Shabab militants began Saturday, he said, and "it's clear" that Kenyan security officials "haven't cleared the building fully."
Kenyan government spokesman Manoah Esipisu said the country's president would make an address to the nation later in the day but said he could give no immediate details on the operation.
Kenyan security officials on Monday evening said they had claimed the upper hand as flames and dark plumes of smoke rose above the Westgate shopping complex for more than an hour after four large explosions.
"Taken control of all the floors. We're not here to feed the attackers with pastries but to finish and punish them," Police Inspector General David Kimaiyo said on Twitter.
Kenya's Interior Minister Joseph Ole Lenku said the evacuation of hostages had gone "very, very well" and that Kenyan officials were "very certain" that few if any hostages were left in the building.
But with the mall cordoned off and under heavy security it was not possible to independently verify the assertions. Similar claims of a quick resolution were made by Kenyan officials on Sunday and the siege continued. Authorities have also not provided any details on how many hostages were freed or how many still remain captive.
Three attackers were killed in the fighting Monday, Kenyan authorities said, and more than 10 suspects arrested. Eleven Kenyan soldiers were wounded in the running gun battles.
Al-Shabab spokesman Sheik Ali Mohamud Rage said in an audio recording posted on a militant website that the attackers had been ordered to "take punitive action against the hostages" if force was used to try to rescue them.
A Western security official in Nairobi who insisted on not being named to share information about the rescue operation said the only reason the siege hadn't yet ended would be because hostages were still inside.
Westgate mall, a vast complex with multiple banks that have secure vaults and bulletproof glass partitions, as well as a casino, is difficult to take, the official said. "They are not made for storming," he said of the labyrinth of shops, restaurants and offices. "They're made to be unstormable."
At least 62 people were killed in the assault Saturday by some 12 to 15 al-Shabab militants wielding grenades and firing on civilians inside the mall, which includes shops for such retail giants as Nike, Adidas and Bose and is popular with foreigners and wealthy Kenyans.
The militants specifically targeted non-Muslims, and at least 18 foreigners were among the dead, including six Britons, as well as citizens from France, Canada, the Netherlands, Australia, Peru, India, Ghana, South Africa and China. Nearly 200 people were wounded, including five Americans.
Fighters from an array of nations participated in the assault, according to Kenya's Chief of Defense forces Gen. Julius Karangi. "We have an idea who these people are and they are clearly a multinational collection from all over the world," he said.
Al-Shabab, whose name means "The Youth" in Arabic, said the mall attack was in retribution for Kenyan forces' 2011 push into neighboring Somalia. African Union forces pushed the al-Qaida-affiliated group out of Somalia's capital in 2011.
The attack at the Westgate mall in Nairobi's Westlands neighborhood was the deadliest terrorist attack in Kenya since the 1998 al-Qaida truck bombing of the U.S. Embassy in Nairobi, which killed more than 200 people.
An extremist Islamic terrorist force that grew out of the anarchy that crippled Somalia after warlords ousted a longtime dictator in 1991, al-Shabab is estimated to have several thousand fighters, including a few hundred foreigners, among them militants from the Middle East with experience in the Iraq and Afghanistan conflicts. Others are young, raw recruits from Somali communities in the United States and Europe.
For years Minnesota has been the center of a federal investigation into the recruiting of fighters for al-Shabab. Authorities say about two dozen young men have left Minnesota since 2007 to join the group. Minnesota's Somali community is the largest in the U.S.
Somali President Hassan Sheikh Mohamud said the attack showed that al-Shabab was a threat not just to Somalia but to the international community.
Mohamed, the Kenyan foreign minister, said her country needs to work with other governments to fight the increasing terrorist threat and "much more with the U.S and the U.K., because both the victims and the perpetrators came from Kenya, the United Kingdom and the United States.
Associated Press reporters Rodney Muhumuza, Ben Curtis, David Rising, Adam Schreck and Jacob Kushner in Nairobi, Kenya, Cassandra Vinograd in London, and Abdi Guled in Mogadishu, Somalia, contributed to this report.