Kenyan security forces say they have taken control of all floors of the Nairobi shopping center attacked by suspected al-Shabab militants.

An explosion and bursts of gunfire were heard coming from the complex on Tuesday morning as speculation grew that the operation was nearing its end, the BBC informs.

Kenyan Foreign Minister Amina Mohamed said Monday that “two or three Americans” and “one Brit” were among the perpetrators of the attack.

She told “PBS Newshour” that the Americans were 18 to 19 years old, of Somali or Arab origin and lived “in Minnesota and one other place” in the United States. The British jihadist was a woman who has “done this many times before,” Mohamed said.

At least 62 people were killed during the siege.

The Somali Islamist al-Shabab movement has said it carried out the attack in retaliation for Kenyan military operations in Somalia.