Terror group Al-Shabaab claimed responsibility
through a statement on Andalus Radio, its main radio channel.
Police Capt. Osman Mohamed said the attack was an attempt to assassinate the new Somali military chief, Gen. Ahmed Mohamed Irfid.
The attack happened on a busy street between the military academy and the ministry of defense headquarters.
The bomber tried to drive into a convoy carrying Irfid, but missed and rammed into a minibus carrying passengers, police said.
Irfid, who was appointed just three days ago by Somali President Mohamed Farmaajo in a major security shake-up, escaped unharmed. Ambulance driver Ahmed Hussein told CNN that some of the injured died on their way to hospital.
Al-Shabaab aims to make Somalia a fundamentalist Islamic state, according to the Council on Foreign Relations. It has been blamed for fatal attacks inside the country and abroad.