The blast happened at a busy intersection near the Wehliye Hotel in Mogadishu, frequented by expatriates working in city.
The cause of the explosion was traced to a parked car that was rigged with explosives.
In a statement shortly after the explosion, the group, said the casualties include soldiers and officers of the Somali army.
At least 20 people were injured.
Abdiazis Ali Ibrahim, a spokesman for the security ministry warned that the casualties could rise given the serious condition of those injured.