Witnesses say sporadic violence between Somali forces and insurgents
has killed at least 12 people and wounded several others in Mogadishu.
Residents said a roadside bomb hit a police vehicle Wednesday, killing four police officers.
Late Tuesday, separate clashes between Somali forces and Islamist militants killed at least five people.
Also Tuesday, residents in the capital said a mortar round hit a house, killing three civilians.
Islamist fighters have led a deadly 17-month insurgency against the government.
Last week, the government and opposition leaders in exile signed a ceasefire agreement in Djibouti. But hardline Islamist leaders and the insurgent group, al-Shabab, have rejected the deal.
Insurgents attacked Mogadishu's airport last week for the second time this month while President Abdullahi Yusuf was on the premises. The president escaped both attacks unharmed.
The fighting has killed thousands of Somalis and displaced more than a million. Aid agencies have warned repeatedly that Somalia is near a humanitarian disaster.
The Horn of Africa country has not had a stable central government since 1991.
Some information for this report was provided by AP and Reuters.