The car exploded next to an Italian cafe on a key thoroughfare in the centre of the city which leads to the presidential palace, in the latest such attack in the violence-scarred country.
“For the moment we have six dead in the explosion, civilians. The car full of explosives blew up next to an Italian cafe,” said the officer, Mohamed Abdulahi.
“The blast was very powerful and there were a lot of people there at the time, I saw several people dead and injured,” added a witness, Abdukadir Ise.
It was unclear whether the car was parked or was driving past at the time that it exploded, according to police sources questioned by AFP.
There was no immediate claim of responsibility for the blast, but Mogadishu is regularly targetted with similar attacks by militant Islamist group Shabaab.
In February the group threatened to escalate attacks in a “vicious war” against the new government of President Mohamed Abdullahi.