MOGADISHU, Somalia — A large explosion outside a school in Somalia’s capital on Thursday has killed at least five people, including students, witness said. Al-Shabab, an extremist group claimed responsibility.

Large parts of Somalia are ruled by an al-Qaida-linked organization, which continues to block efforts to rebuild the Horn of Africa nation.

The explosion sent smoke from the sky above Mogadishu’s busy morning traffic.

Abdulkadir Adan from the Amin ambulance company confirmed that five people died to The Associated Press. The service added that 15 other wounded persons were rushed by the Amin service to a hospital.

“This is a tragedy,” he said.

The school was blasted in photos, and emergency personnel can be seen peering through the collapsed roof beams.

Al-Shabab stated in an Andalus radio statement that it had targeted Western officials being transported by the African Union peacekeeping force. Hassan Ali, a witness told the AP that the official were being escorted by a private security firm and that he had seen four of them wounded.

Somalia’s political and security future are in serious doubt due to the attack. The AU peacekeeping forces were supposed to be withdrawn from Somalia. However, there are concerns that the mission of these troops could be extended due to concern about Somali forces’ inability to secure their country. Early this year, the U.S. announced that it had completed its troop withdrawal form Somalia.

A delayed presidential vote had been scheduled for February. However, it looks like the election will now be held next.