The Islamist group al-Shabab has claimed responsibility for the killing of a senior Somali military official and his bodyguard in south Mogadishu.
Mogadishu residents run the constant risk of mortar attack
Colonel Farah Abdulle Ga'al and his bodyguard died when a landmine concealed under the colonel's chair exploded after he arrived at work.
The incident occurred while fierce fighting continued between insurgents and government forces.
Ethiopia-backed forces took control of Mogadishu from Islamists a year ago.
The UN says that 60% of the city's residents have fled clashes in the city.
On Sunday night, insurgents attacked three bases belonging to African Union peacekeepers, Somali and Ethiopian forces.
Ethiopian troops reportedly responded with heavy artillery fire.
At least two shells exploded in Bakara market, close to where the colonel and his bodyguard were killed.
"He used to be there every morning to inspect the security operation, but this morning the land mine blew him up, it was a barbaric act and inhumanity," said Mogadishu's Deputy Mayor Abdi-fitah Shawey.
Al-Shabab posted the claim of responsibility on its internet site.
Earlier on Sunday, a woman and her five children were killed when a mortar round exploded in north Mogadishu.
Another two people were reported to have been killed in the southern part of the city.
Somalia has been politically fragmented since 1991 and the country's transitional government, faced with an insurgency, is dependent on international aid and Ethiopian military support.