A government official also said that four people were also wounded when a gunbattle erupted outside the Globe hotel in the centre of the city.
The hotel often hosts members of the interim Somali government.
In a separate incident, two soldiers were reportedly killed in a gunfight with local clan militiamen in Laanta Bur, just outside Mogadishu, according to Ismail Yusuf, a local man.
The government had no immediate comment.
Pattern of attacks
The attacks are the latest to target the government and its allies, including the Ethiopian soldiers that are helping it hold the capital.
The interim government, supported by Ethiopian airpower and armour, drove the Union of Islamic Courts group out of Mogadishu in late December, ending its six-month rule of the capital and much of southern Somalia.
Members of the Islamic Courts who survived scattered back to their clan areas and have vowed to fight against the government and a planned 8,000-strong African Union (AU) peacekeeping force.