(CNN) -- A suicide bomber hit an African Union Mission in Somalia convoy on Monday, killing 16 people, Lower Shabelle Gov. Adukadir Mohamed Sidi said. Sidi said the explosion destroyed two buses traveling behind the military convoy, which was transporting the governor as he traveled back from Mogadishu. The blast killed 16 civilians and injured 22 people, including two soldiers, he said. The Al-Shabaab terrorist group claimed responsibility for the attack and said Americans and South Africans were among those killed. The bombing comes a week after a U.S. airstrike claimed the life of the group's leader, Ahmed Godane. The group appointed a new leader last week and said Godane's death would not stop its attacks. Somalia has been on high alert for strikes since. Al-Shabaab names successor to slain leader; Somalia on alert . CNN's Faith Karimi, Jason Hanna and Michael Pearson contributed to this report.
16 killed in Somalia suicide bombing targeting governor's convoy . Two African Union Mission in Somalia troops are wounded, he said . Al-Shabaab claims responsibility for attack .