At least 20 people have been killed and 58 injured in a battle between anti-government fighters and African peacekeepers in Mogadishu, Somalia's capital, medical workers say.
According to witnesses, clashes broke out on Thursday after fighters launched mortar bombs at the city's international airport, as Sharif Ahmed, the country's president, flew out of the country.
Ali Muse, head of Mogadishu's ambulance services, told the AFP news agency it was "the worst such incident recently" in the city.
"We have seen at least 20 dead bodies lying in the streets, most of them
civilians," he said.
"Heavy shelling was hitting civilian populated areas, including Bakara market, Holwadag and Hodan."
Clashes are said to have broken out after opposition fighters fired mortar bombs at the president's plane, triggering a response from African Union peacekeepers.
Sharif, who was heading to Uganda for an African Union summit, was not hurt in the fighting, sources told news agencies.
Fighting in Somalia has killed 19,000 civilians since the start of 2007 and driven another 1.5 million from their homes.
But both sides of the conflict have been accused of indiscriminate shelling of civilian areas.
Al-Shabab, a powerful group of fighters with suspected links to al-Qaeda, and a political group called Hezb al-Islam are fighting to overthrow the fragile UN-backed government.
The groups control much of southern and central Somalia, and want to impose their version of sharia (Islamic law) in the country.
Somalia has seen more than 15 transitional governments come and go since civil war broke out in 1992.