Fifteen people were killed when armed men stormed an upscale hotel complex in Kenya’s capital, Nairobi, on Tuesday, according to Reuters. An American man, a British man, and 11 Kenyans were among the dead, according to a mortuary worker. Somali militant group al-Shabab has taken responsibility for the assault, which authorities have called a “terror attack.” Kenyan security forces secured the buildings where gunmen mounted the deadly attack, and expect the death toll to rise as bodies are recovered, according to government officials. “The security teams have evacuated scores of Kenyans and other nationalities from the (hotel and office) buildings,” Ministry of Interior and Coordination of National Cabinet Secretary Fred Matiang’i said, according to CNN. “We are now in the final stages of mopping up the area and securing evidence and documenting the consequences of these unfortunate events.”

Witnesses told BBC that four armed men entered the hotel complex, and a person inside the complex told Reuters they were “under attack” before hanging up the phone. Footage from the scene showed cars set on fire and armed officers escorting office workers to safety as the sound of shots rang out. “I just started hearing gunshots, and then started seeing people running away raising their hands up and some were entering the bank to hide for their lives,” a woman in a neighboring building told Reuters. The attack happened in an upscale neighborhood of the capital city. Victims are now being escorted out of the area by armed officers, BBC reports. Video from CBS News showed smoke rising from the area in the Westland district of the city near the DusitD2 spa hotel and office spaces. Nairobi police commander Philip Ndolo confirmed they had already cordoned off the area due to a suspected robbery.