NAIROBI, Kenya (CNN) -- Heavy gunfire sent aid workers and journalists scrambling outside Nairobi's Westgate Shopping Mall on Monday afternoon, more than an hour after a Kenyan government official said security forces had taken full control of the four-story building from terrorists.
It was unclear if any hostages remained inside the building, but authorities expect the number to be "very, very minimal," if any remain, Interior Minister Joseph Ole Lenku said at a news briefing.
Most had already been evacuated, he said Monday, the third day of the siege.
The Kenyan Red Cross said that 62 people had died since the Saturday attack by gunmen from the Somalia-based Al-Shabaab terror group. The agency had previously reported 69 deaths. Some bodies had been counted twice, it said on Twitter.
Dark smoke that rose from the building after Monday's assault was from fires set by the gunmen to distract forces from the assault, Lenku said.
Terrorists appear to be on the run inside the mall, which Lenku said had been sealed off to prevent their escape.
"We are in charge of the situation, our people are safe," he said.
Kenyan authorities say they have killed three of the terrorists.
The Interior Ministry told CNN that authorities had arrested "around four" people on suspicion of involvement in the attack. The agency later tweeted that more than 10 were arrested. The arrests were made at the airport, the agency said on Twitter.
Eleven Kenya Defense Forces soldiers have been injured, police said on Twitter.
The country's Immigration Department said in a tweet that it had increased security at entry and exit points.
Before the assault, terrorists were believed to have about 10 hostages on one level of the mall, security officials said.
An unspecified number of hostages then were freed overnight, the head of the Kenyan police force said.
Outside the security perimeter around the mall, volunteers waited Monday for their chance to go inside and recover bodies.
At a community center nearby, a distraught woman continued to seek information about her missing husband, a mall employee.
Meanwhile, the FBI was looking into claims by Al-Shabaab of American citizens being involved in the attack but has not confirmed the claims, law enforcement officials told CNN.
The terrorist attack began at midday Saturday, Nairobi time, with an estimated 10 to 15 gunmen. A youth cooking competition was taking place in part of the mall at the time. Two attackers were killed Saturday.
Witnesses said the gunmen went from store to store, shooting people, and then took hostages.
Survivor Bendita Malakia, a North Carolina woman who moved to Nairobi in July, told CNN affiliate WAVY that she took refuge behind the closed metal gates of a store with dozens of others.
"While we were back there, you could hear them methodically going from store to store, talking to people and asking questions," she said. "They were shooting, screaming. Then it would stop for a while and they would go to another store."
Hospital volunteer Abiti Shah told CNN on Monday that witnesses told her the arrival of the gunmen was like "a Hollywood action scene."
"They just started firing in the air," Shah said, retelling the witness accounts.
Al-Shabaab has claimed that the attackers targeted non-Muslims and vowed they would not negotiate for the hostages' lives. CNN security analyst Peter Bergen said the terrorists apparently took hostages only to prolong the siege and win more media attention.
As Kenyan police and military tried to end the standoff in its third day, authorities elsewhere were collecting names and details and planning to track down those in Al-Shabaab behind the attack.
Most of the dead were said to be Kenyans.
Four British citizens, two French nationals and two Canadians, including a diplomat, also died, their governments said.
Those killed include:
• A 33-year-old Dutch woman, said Friso Vijnen, according to a Dutch Foreign Affairs Ministry official.
• A major African poet, author and Ghanian statesman, Kofi Awoonor, Ghana's president said.
• The nephew of Kenyan President Uhuru Kenyatta and the man's fiancee.
• A Peruvian doctor, Juan Jesus Ortiz, who had previously worked for the United Nations Fund for Children and lived in Kenya doing consulting work, the country's Foreign Affairs Ministry said.
Kenyatta said more than 175 people had been wounded. Five were Americans, the State Department said Sunday.
Elaine Dang, 26, a University of California, Berkeley, graduate from San Diego, underwent surgery to her chest, arms and legs.
"I'm OK, I'm very grateful to be alive," she told CNN affiliate KFMB-TV
She said two friends died in the attack.
Dang, who has worked for humanitarian organizations, now is the general manager for Eat Out Kenya.
She said she hoped Americans would not form negative opinions about Kenya.
"I'm very prideful for the country, and I love Kenyans," she said.
Three injured security forces also were seen being
taken out of the mall, but the severity of their injuries was unclear.
Before its Twitter account was suspended, Al-Shabaab issued a list of nine names it said were among the attackers. It said three were from the United States, two from Somalia and one each from Canada, Finland, Kenya and the United Kingdom.
A senior State Department official said that the United States was trying to determine whether any of the attackers were American. While they were still working to verify the claims, authorities said they were becoming more confident that American citizens may be involved.
Federal officials and Somali-American leaders in Minneapolis have reported that Al-Shabaab has recruited young men there to go to Africa to fight.
While senior Kenyan intelligence sources told CNN on Monday that surveillance video from inside the mall appears to show a white woman taking part in the attack, Lenku, the Kenyan interior minister, told reporters that all of the attackers were men.
Some of the terrorists apparently dressed as women, he said.
However, the sources said that the woman is actively involved in the attacks and that they believe she is British.
The report came after earlier speculation that the Al-Shabaab-affiliated "White Widow," Samantha Lewthwaite, may have been involved in the attack.
Lewthwaite's husband, Germaine Lindsey, was one of the suicide bombers killed in the 2005 attack on London's transportation system. His Buckinghamshire-born widow is wanted by Kenyan authorities for her alleged role as an Al-Shabaab and al Qaeda-linked financier.
State House spokesman Manoah Esipisu earlier said that "nothing is being ruled out" when it comes to Lewthwaite's possible involvement.
Such involvement would be "very unusual," said Bergen, the security analyst.
"Typically these groups are misogynist," he said. "Their view is the woman should be in a home and shrouded in a body veil."
Lenku said Monday that the effort to roust the terrorists was a Kenyan operation, but government sources told CNN that Israeli special forces also were at the scene.
Kenyatta, the Kenyan president, vowed Sunday to punish those responsible for the attacks.
"They shall not get away with their despicable, beastly acts. Like the cowardly perpetrators now cornered in the building, we will punish the masterminds swiftly and indeed very painfully," he said.
U.S. Secretary of State John Kerry promised an American investigation.
"Obviously, it's an enormous offense against everybody's sense of right and wrong," Kerry said. "It represents the seriousness and the breadth of the challenge we face with ruthless and completely reckless terrorists, and we're going to pursue them."
The mall siege is the deadliest terror attack in Kenya since al Qaeda blew up the U.S. Embassy there in 1998, killing 213 people.
Al-Shabaab is al Qaeda's proxy in Somalia.
Since Kenya launched attacks against Al-Shabaab in Somalia in 2011, the group has hurled grenades at Kenyan churches, bus stops and other public places.
Last year, the Kenyan military was part of a peacekeeping force that defeated Al-Shabaab forces to liberate the key Somali port of Kismayo.
Michael Pearson reported and wrote from Atlanta; Zain Verjee and Nima Elbagir reported from Nairobi. CNN's Arwa Damon, Lillian Lesposo, Holly Yan, Greg Botelho, Brian Walker, Jackie Castillo and David Simpson also contributed to this report.
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