The blast also damaged nearby houses blew off the roof of a mosque and caused a nearby school to collapse BBC reported.
Police officer Abdullahi Hussein said a suicide bomber had rammed a car into the district office in Howlwadag district.
The militant group al-Shabab which has waged an insurgency for more than 10 years has claimed to be behind the attack.
In a similar incident on July 14 seven people were killed and several others injured in two explosions near the presidential palace in Mogadishu.
--IANS mag/sed
