A man suspected of carrying out the shooting has been arrested and taken into custody.
Shortly before he was killed, Abdulle gave an interview to a Mogadishu radio station announcing the capture of four gunmen who had been blamed for a string of attacks.
Kismayu was the last bastion of the Islamic Courts Union which controlled much of southern and central Somalia until it was forced out by the weak interim government backed by Ethiopian forces.Mortar attack
In Mogadishu, a barrage of mortar shells fell on a civilian district after missing their apparent target in the seaport, where an African Union-chartered freighter carrying military equipment was due to dock.
A police official at the port said: "The insurgents have fired 13 mortar shells at the seaport, but no one was injured inside here. Most of the shells landed outside the port compound.
"There was a small gunfire after gunmen ambushed Ethiopian forces near the seaport, but no one was injured."
Relatives said that a bystander had been killed during the attempted ambush.
Abdulaziz Mohamed, a resident, told AFP news agency that most of the 13 mortars hit a restaurant in the Hamel Jejab neighbourhood.
"Three people were wounded - two of them seriously - when a mortar shell landed in a restaurant where I was eating," he said.
Near-daily attacks in Mogadishu have been blamed on remnants of the Islamic courts and the interim government says the next fortnight will be crucial in proving it can make the capital secure in time to hold a meeting of clan leaders, elders and former militia leaders there next month.
United Nations aid agencies working in Somalia have said that more than 40,000 people fled the fighting in Mogadishu in February alone.