Mogadishu, Somalia’s bullet-pocked capital, is awash with loosely organized militias and thousands of undisciplined troops, and there have been several cases of peacekeepers and government soldiers accidentally killing civilians. Also, the peacekeepers and government forces sometimes fire in the air to clear jammed intersections, because there are no working traffic lights in Mogadishu or just about anywhere in Somalia.

“The African Union truck came after the car and started firing,” said a woman who saw the attack and who provided only her first name, Halima.

Meanwhile, fighting has erupted in Galkaiyo, a town in central Somalia that is divided between the Puntland semiautonomous government and a separate, clan-based administration. Puntland officials said they were fighting Islamist militants who had killed one of their top commanders. But officials with the Galmudug state government, which is a small clan-based administration based in Galkaiyo, said the fighting was a clan dispute.

The fighting in Galkaiyo has killed more than 20 people and wounded dozens, threatening to complicate an already tricky political conference that begins on Sunday. The United Nations has invited several dozen Somali politicians, including cabinet members of the Transitional Federal Government and leaders from Puntland and Galmudug, to Mogadishu to devise a “roadmap” to prepare for the end of the transitional government, whose mandate expires next year. The politicians, many of whom have been accused of pilfering millions of dollars, are expected to carry out an ambitious program of reforms, including the writing of a new constitution.