Somali officials say a suicide bomber killed at least five people on Wednesday outside a military compound in Mogadishu, the latest in a series of attacks in the violence-ridden capital.
Military officials and witnesses say the attacker detonated his explosives after being approached by security forces outside Villa Baidoa, a government military base in central Mogadishu.
No one has yet claimed responsibility for the attack, though the city has frequently been targeted by the Somali insurgent group al-Shabab.
On Monday, a series of blasts killed at least six people in Mogadishu, including two people at a hospital for women and children.
In recent months, Somali forces backed by African Union troops forced al-Shabab from Mogadishu, but the insurgents have continued to wage guerilla-style warfare in the capital.
Meanwhile, the U.S. State Department says it is "extremely concerned" about al-Shabab's announcement to ban 16 international aid organizations.
In a statement Tuesday, the State Department joined U.N. Secretary-General Ban Ki-moon in condemning the group, saying al-Shabab is putting millions in need of emergency assistance in Somalia at even greater risk.
Al-Shabab has accused the aid agencies of promoting secularism, immorality and what it described as "the degrading values of democracy in an Islamic country."
Among the forbidden agencies are six U.N. organizations, including the World Health Organization, the U.N. Children's Fund and the U.N. refugee agency.
The State Department said the aid groups are only working to save lives in Somalia, and called on all parties to immediately allow access to those who need emergency assistance.
The United Nations says famine still persists in three regions of Somalia with nearly 250,000 people at risk of starvation.
The al-Qaida-linked militant group has been fighting since 2008 to topple Somalia's weak central government and install one based on its radical interpretation of Islamic law. The group still controls large sections of central and southern Somalia.
Troops from Kenya, the AU and Somalia's transitional government are all battling al-Shabab. Ethiopia said last week it may also contribute troops to the fight.
Some information for this report was provided by AP and AFP.