Witnesses say a roadside bomb has struck a vehicle carrying African Union peacekeepers in Somalia's capital, Mogadishu.
Initial reports said the vehicle was destroyed in Friday's attack and that four AU soldiers were either killed or wounded.
About 2,000 soldiers from Uganda and Burundi are serving with the AU peacekeeping mission in Somalia.
The troops, stationed in Mogadishu, have had little effect on the fighting between Islamist insurgents and pro-Somali government forces.
More than a year of fighting has killed thousands of Somalis and displaced hundreds of thousands more, most of them from Mogadishu.
Separately Friday, Somali gunmen have released a Kenyan lecturer, more than a week after he was captured in the capital city. Staff members at Mogadishu University say the lecturer, Moses Nyandusi Matundura, is in good condition.
Somalia has endured more than 17 years of chaos and conflict since the 1991 fall of the country's last stable government.
Some information for this report was provided by AFP.