The dead included many students and two Turkish nationals, Somalia's foreign minister said, adding that dozens were injured.
Saturday is a working day in the Muslim country and the explosion occurred during the morning rush hour. Rescuers carried bodies past the twisted wreckage of a vehicle and a minibus taxi smeared with blood.
A report by the international organisation, which did not want to be named, said the death toll was more than 90 and that university students and 17 police officers were among those killed. A Somali MP also tweeted that he had been told the death toll stands at more than 90.
No one immediately claimed responsibility for the blast but the city's mayor blamed Al Qaeda-linked group Al Shabaab. Three witnesses said that a small team of Turkish engineers were present at the time of the blast, constructing a road into the city. Turkey's foreign ministry confirmed the death of two of its nationals. - Reuters