"So far two civilians have died and two others were injured," Mohamed Hussein, a police officer, told Reuters.
Captain Mohamed Hussein says the bomber detonated near the Weheliye hotel on Mogadishu's busy Maka Almukarramah road.
Ambulances have rushed to the scene.
There has been no immediate claim of responsibility however the al-Qaeda-linked Islamic extremist group al-Shabab often carries out such attacks.
Despite being ousted from most of its key strongholds in south and central Somalia, the extremist group continues to carry out deadly guerilla attacks across the country.
Police officer Nur Osman later told Reuters that two people were wounded.
