A suicide bomber killed at least four people Wednesday after ramming a car filled with explosives into a UN convoy in the Somali capital of Mogadishu. The attack took place near the airport, which is heavily guarded and is the entrance to the “green zone” where many foreign embassies are based. There are expected to be more casualties. The al Qaeda-affiliated al-Shabab rebels, who claimed responsibility, have conducted multiple bombings and attacks in the city. The airport is the base of 22,000 African Union troops fighting al-Shabab.