A woman who had been held hostage is assisted outside the mall. Tony Karumba/AFP/Getty Images

A Kenyan soldier gives the thumbs up on Tuesday after clearing the top floor balcony and interior of the mall. Carl de Souza/AFP/Getty Images

Smoke rises from the building as the Kenyan forces attempt to retake the mall.

A woman who had been held hostage is assisted outside the mall. Tony Karumba/AFP/Getty Images

A wounded man sits in shock in the parking lot of the mall. Goran Tomasevic/Reuters

Civilians are evacuated from the shopping mall following the attack Saturday. Nichole Sobecki/AFP/Getty Images

Civilians escape the mall as police continue to hunt for the attackers. Siegfried Modola/Reuters

A shopper cries as she is evacuated from the mall. Thomas Mukoya/Reuters

A mother and her children hide from gunmen during the early moments of the attack. Siegfried Modola/Reuters

A police officer secures his position beside a clothing store window after Somali gunmen stormed the Westgate Shopping Center in Nairobi and opened fire on Saturday, September 21, 2013. Siegfried Modola/Reuters

Early Sunday morning in Kenya -- 12 hours after a deadly shooting attack left at least 39 people dead in an upscale mall in the capital Nairobi -- gunmen from the armed Somali group al-Shabab remained holed up inside with an unknown number of hostages, according to The Associated Press.

Kenyan President Uhuru Kenyatta, who said members of his own family were among the dead, called the security operation under way "delicate" and said a top priority was to safeguard hostages.

Al-Shabab claimed responsibility for the Saturday shooting, which also injured more than 150 people.



The Somali group confirmed to Al Jazeera that it was behind the deadly attack, which began shortly after noon local time Saturday, after posting a series of ominous statements on Twitter.

Throughout Saturday, security forces searched for shoppers hiding within the Westgate mall, popular with wealthy Kenyans and expatriates.

According to Secretary of State John Kerry, American citizens were among those injured. He said there were no reports of American deaths, but one of the people killed was the wife of a foreign service national who is working for the U.S. Agency for International Development.

"Today's terrorist massacre of so many innocents is a heartbreaking reminder that there exists unspeakable evil in our world which can destroy life in a senseless instant," Kerry said in a release. "We have offered our assistance to the Government of Kenya and stand ready to help in any way we can."

The State Department also said that according to local media reports about 10 gunmen attacked the mall.



U.S. National Security Council spokeswoman Caitlin Hayden issued a statement condemning the attack.

"The perpetrators of this heinous act must be brought to justice, and we have offered our full support to the Kenyan government to do so," Hayden said.

Kenyan military and police surrounded the mall Saturday, which had been hosting a children's day event, and helicopters flew overhead as gunmen remained inside hours after the attack occurred.

President Kenyatta said via Twitter Saturday that one of the gunmen had been arrested. Later Saturday, he reported that the gunman had died from bullet wounds, according to Reuters.

