Kenyan officials say an unknown number of hostages are still being held after a suspected terrorist attack in a shopping mall.
Kenya's president Uhuru Kenyatta, (pictured) has urged people in Nairobi to remain calm after the attack left 39 people dead and 150 injured. He vowed to "hunt down the perpetrators wherever they run to."
The Somali militant group Al Shabaab has claimed responsibility.
On its Twitter feed, al-Shabab - which has links to al-Qaeda - said it was behind what it called the "Westgate spectacle".
Kenyan officials said "major operations" were under way with police and soldiers preparing an apparent bid to bring an end to the stand-off.
