Heavy machine gun and rifle fire broke out at the port and airport in Mogadishu on Monday, disrupting the unloading of food for Somali famine victims.
U.N. officials reported an undetermined number of deaths at the Indian Ocean port. It was not known whether anyone was killed at the airport.
Lisbeth Palme, widow of assassinated Swedish Prime Minister Olaf Palme, arrived at the airport from Nairobi just as shooting began at the nearby port. Mrs. Palme, who heads the U.N. Children's Fund in Sweden, was quickly taken into the capital.
Tommy Thomson, 49, of South Africa, who coordinates airport operations for the U.N. World Food Program, said that about an hour after Mrs. Palme left the airport, fighters started firing .50-caliber machine guns across the tarmac.
A Belgian C-130 cargo plane and a Canadian C-130 were unloading relief goods when the shooting started. Both managed to get about half their cargo on the ground before taking off, Thomson said.
Clan fighting, banditry and looting have crippled international efforts to feed Somalia's starving people. Some aid officials estimate as much as half the estimated 181,500 tons of food delivered to the country has been stolen.
More than 100,000 Somalis already have died from the effects of drought and warfare and up to 2-million more are threatened.
The cause of Monday's fighting was unclear.
The first contingent of United Nations troops, 500 troops from Pakistan, arrived in the country last week but have yet to deploy.