Several people are reported to have been killed in southern Somalia as violence erupted following the arrest of a former al-Shabab commander set to contest regional elections.
At least 11 people, including soldiers and civilians, died in Baidoa during clashes involving supporters of Mukhtar Robow, sources told the BBC.
The government has accused Mr Robow of being a security threat.
He is seeking the presidency of South West state in next week’s election.
News of Mr Robow’s arrest early on Thursday triggered street protests in Baidoa, the regional capital.
A Somali radio station tweeted images of roads strewn with burning tyres and rocks.
The BBC’s Ibrahim Adan in the capital, Mogadishu, says the nationality of the soldiers who were killed is not clear. Ethiopian troops, who form part of the African Union force in the country, have a base in the city.
Mr Robow was a spokesman for the jihadist al-Shabab group and once served as its deputy leader before defecting last year.
The federal government banned him from contesting the state elections but the electoral commission gave him the go-ahead.
Correspondents say he has posed a major threat to the influence of the federal government in the region.
Following his arrest, a government statement said he had been organising a militia in Baidoa.
“These actions indicate that he never relinquished his extremist ideologies and is ready to harm the Somali people again,” the statement said.
Mr Robow is supported by several clans in the area and is regarded as a serious candidate for the regional election. His supporters were infuriated by his detention.
“This is a violation of democracy, Robow was standing in his region and his people wanted him. The government has no right to arrest him,” Baidoa resident Mohamed Sheik Ali told AFP news agency.