A suicide bomber from Somalia's Shebab insurgents killed at least 12 people and wounded 27 others Monday by ramming a vehicle packed with explosives into a convoy of African Union troops, officials said. The attack, the latest in a string of killings, comes exactly one week after a US airstrike killed the chief of the al Qaeda-linked Shebab rebels, Ahmed Abdi Godane, prompting threats of retaliation from the extremists. "The car packed with explosives hit one of the armoured trucks... 12 civilians in a minibus were killed, and 27 others were wounded," local governor Adukadir Mohamed Sidi told AFP.