At least half of the deaths were children under the age of 5, according to the report by health researchers, the United Nations and the Somali government.
An extremist group, Al Shabab, claimed responsibility for the attack at the hotel in the Somali capital. There were few immediate reports of casualties, but the siege was still underway.
The twin explosions were the deadliest terrorist attack in the country in five years and underscored the growing threat posed by the terrorist group Al Shabab.