MOGADISHU, Somalia (AP) — A suicide bomber detonated an explosives-laden car outside the United Nations Mine Action Service offices in Mogadishu, killing 10 people, including seven U.N. guards, a Somali police official said Tuesday.

Unlike previous attacks blamed on the al-Qaida-linked militant group al-Shabab, gunmen did not accompany the suicide bomber, Captain Mohamed Hussein said.

He said that the suicide car bomber tried to speed through the barrier at the U.N. office but guards shot at the car.

Hussein said a second suicide blast targeted a checkpoint manned by Somali security forces near the African Union base in Mogadishu. Casualties there remain unclear.

Al-Shabab has claimed responsibility for the blasts, according to the group's Andalus radio station. Al-Shabab is waging an insurgency against Somalia's weak U.N.-backed government.