Unidentified gunmen have hurled grenades at government security forces in Somalia's capital, killing three civilians, including a pregnant woman.
Authorities say Tuesday's incident occurred near Mogadishu's Bakara market - the scene of almost daily clashes between insurgents and government troops.
Somali authorities have struggled to bring security to the capital despite repeated crackdowns by the government and allied Ethiopian troops.
The insurgents are believed to be linked to the Islamist movement that ruled Mogadishu for several months last year.
Also Tuesday, the U.N. refugee agency appealed for $48 million to help Somalis displaced or driven abroad by the violence.
The agency estimates that 500,000 Somalis are internally displaced, and that at least 62,000 more have fled since January to neighboring countries, mainly Kenya, Ethiopia and Yemen.
The agency says it is currently helping more than 300,000 Somalis in the region. Spokeswoman Jennifer Pagonis said that number may rise if aid workers get improved access to displaced people in south and central Somalia.
Islamists controlled Mogadishu and many other Somali cities until late last year, when the government ousted them with the help of Ethiopian forces. The government has since struggled to assert its authority in the face of an insurgent campaign.
Somalia has not had an effective central government in 16 years, since warlords overthrew dictator Mohamed Siad Barre in 1991.
Some information for this report was provided by AP and AFP.