At least eight people have been killed and 15 others injured in an explosion in a vegetable market in south central Somalia, a police official and witnesses said.
Abdullahi Ahmed, a police officer in Baidoa, said the blast came from a roadside bomb buried along the street. But witness Nur Yusuf said the device was concealed in a flask placed along the street where he sells vegetables.
Mr Ahmed said the death toll is likely to rise, and confirmed one suspect had been arrested.
Baidoa was a major base for Somali militant group al-Shabab until Ethiopian troops and Somali soldiers seized the key town in February.
Some 100 soldiers are now being sent to Baidoa - Somalia's third-largest city - as an advance team for 2,500 troops soon to be deployed there. The AU troops will be stationed alongside Ethiopian troops already in Baidoa.