Capt. Mohamed Hussein says the blast targeted a tax collection center during the morning rush hour in Mogadishu as Somalia returns to work after its weekend.
There is no immediate claim of responsibility for the blast. However, the al-Qaida-linked al-Shabaab group often carries out such attacks.
The director of the private Aamin Ambulance services in Mogadishu, Abdukadir Abdirahman warned that the number of dead is likely to go higher.