Three large explosions were heard at a shopping mall in Kenya's capital early Monday as a hostage standoff involving al Qaeda-linked terrorists which left at least 68 people dead entered its third day.
The blasts occurred shortly after 6 a.m. ET. Black smoke was also seen billowing from the complex. Heavy bursts of gunfire had been heard early Monday.
"Two terrorists have been killed as a result of our activities this morning and several injured," Interior Cabinet Secretary Ole Lenku told a press conference on Monday.
Lenku added that some of the militants who seized Nairobi's Westgate Mall on Saturday had been dressed as women.
The military-style, lunchtime assault by squads of al-Shabab attackers hurling grenades and spraying automatic fire also resulted in at least 175 injuries, including many children.
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Al-Shabab said the assault, which targeted non-Muslims, was in retribution for Kenyan forces' 2011 push into neighboring Somalia.
A military official said late Sunday that "most" of the hostages had been freed.
David Kimaiyo, the inspector general of Kenya’s police, posted on his Twitter account Monday that more hostages had been rescued overnight and "very few are remaining."
He added: "We are also closing in on the attackers."
Kenya Police's Twitter account also urged the public to stay away from the shopping mall "as we intensify our operations."
The FBI said it was investigating reports that as many as five Americans were among the group of al Qaeda-linked terrorists who raided the Westgate mall in Nairobi on Saturday.
Kenyan security forces were being assisted by Israeli and Western experts. "We will not negotiate with terrorists," said Colonel Cyrus Oguna, a Kenyan military spokesman.
Slideshow: Gunmen attack mall in Kenya
Earlier, an al-Shabab spokesman claimed Kenyan security forces had attempted an unsuccessful raid on the complex, which features several Israeli-owned shops.
"Israelis and Kenyan forces have tried to enter Westgate by force but they could not," Sheikh Ali Mohamud Rage said in an online audio statement. "The mujahedeen will kill the hostages if the enemies use force.”
Reuters said the group of terrorists numbered between 10 and 15. Witnesses said the attackers had AK-47 rifles and wore ammunition belts.
One woman, who gave her name as Cecilia as she emerged from the mall Sunday, told Reuters she had seen three of the attackers.
"They were shooting from the exit ramp, shooting everywhere," she said. "I saw people being shot all around me, some with blood pouring from bad wounds. I was just praying, praying, 'God, keep me alive' and that my day hadn't come."
Video taken by someone inside the mall's main department store when the assault began also emerged. The video showed frightened and unsure shoppers crouching as long and loud volleys of gunfire could be heard.
Kenyan officials have taken a more aggressive position against the terrorists. NBC's Ron Allen reports.
“My father was sitting down for coffee with his brother when they heard gunfire coming from the street,” one Kenyan told the U.K.’s Independent newspaper after escaping the mall with his family. “They immediately hit the ground and then heard three loud explosions. The people at the next table were all shot and died.”
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Several British newspapers such as the Daily Mail suggested that the notorious “White Widow” – a British Islamic convert called Samantha Lewthwaite whose husband was one of the July 7, 2005, bombers targeting London's public transport network – was behind the attack. She is known to have spent time in Kenya.
However, the British Foreign Office said it was unwilling to speculate on Lewthwaite's involvement.
This weekend’s assault is the biggest attack in Kenya since al Qaeda's East Africa cell bombed the U.S. Embassy in Nairobi in 1998, killing more than 200 people.
No U.S. citizens have been reported dead, although five Americans have been injured. Several foreigners, including four Britons and a Canadian diplomat, were killed. "We should prepare ourselves for further bad news," British Prime Minister David Cameron said.
Elaine Dang, 26, was among the Americans injured in the attack, NBC San Diego reported.
Kenya sent troops into Somalia in October 2011 to pursue militants whom it accused of kidnapping tourists and attacking its security forces.
Al-Shabab's last big attack outside Somalia was a double bombing in Uganda, targeting people watching the World Cup final on television in Kampala in 2010, killing 77 people.