Goran Tomasevic / Reuters

Women ran for safety while carrying children as armed police hunted gunmen who went on a shooting spree in Nairobi's Westgate shopping centre on Sept. 21.

Al-Shabab posted a statement on its official Twitter feed shortly after the attacks, saying the deaths were retribution for Kenya sending soldiers to Somalia. The group said the battlefield would now be in Kenya.

The U.S. State Department also said that Americans were allegedly hurt at the scene.

"We have reports of American citizens injured in the attack, and the U.S. Embassy is actively reaching out to provide assistance," State Department spokeswoman Marie Harf said in a statement.