Al-Shabab suicide bomber kills at least 12 in Somalia

At least 12 civilians were killed and over 20 wounded in a suicide attack on Monday launched by Al-Shabab against African Union troops in Somalia. The attack marks the first significant assault by the armed group since a U.S. airstrike killed its top leader last week, authorities said. 

Reports indicate that four Americans were among those who died during the attack, which was carried out near the Elasha Biyaha settlement in Somalia's Lower Shabelle region.

A suicide bomber detonated his explosive-laden car next to a convoy of African Union forces moving near two minibuses, Somali police official Hassan Ali said. 

Then, amid the confusion, another bomb went off when a second suicide attacker rammed his car into a convoy escorting Abdifatah Shaweye, the Mogadishu intelligence commander, who was in the area to inspect the scene of the first blast. Shaweye suffered "slight wounds" and was rushed to a Mogadishu hospital. There were no fatalities from the second blast, Ali said.

Somalia's government warned over the weekend that there was a probability of attacks following the killing of Al-Shabab leader Ahmed Abdi Godane, who was confirmed dead by the U.S. on Friday following a Monday airstrike. Possible targets included medical and educational institutions, said Gen. Khalif Ahmed Ereg, Somalia's national security minister, in a televised speech on Friday.

Mortar shells struck a Mogadishu neighborhood on Sunday, the day after Al-Shabab named a new leader and vowed to avenge the death of Godane. The armed group said in a statement over the weekend that it remains aligned with Al-Qaeda, according to the SITE Intelligence Group, which monitors statements by armed groups.

"Avenging the death of our scholars and leaders is a binding obligation on our shoulders that we will never relinquish nor forget no matter how long it takes," said the Al-Shabab statement, according to SITE.

Godane, who was also known as Mukhtar Abu Zubeyr, was Al-Shabab's spiritual leader. The U.S. had offered a reward of up to $7 million for information leading to his arrest.

Godane had publicly claimed Al-Shabab was responsible for an attack on a mall in the Kenyan capital, Nairobi, in which 67 people were killed last year.

Backed by African Union forces, Somali government troops recently launched a military offensive aimed at ousting Al-Shabab militants from their last strongholds in southern Somalia, including the coastal city of Barawe, where military officials say Al-Shabab plots attacks across Somalia. Scores of people have been killed this year, including lawmakers targeted by the group for assassination. 

Al Jazeera and wire services