A bomb exploded inside the largest market in the Somali capital on Tuesday, wounding at least five soldiers aboard a military vehicle, police said.

The bomb was concealed inside a Somali military pick-up truck in Mogadishu’s sprawling Bakara market, Mogadishu police official Mohamed Hussein said on Tuesday.

It was not immediately clear who was responsible for the attack or how the bomb was detonated, but the al-Qaida-linked rebels of al-Shabab frequently stage similar attacks in Mogadishu and elsewhere in Somalia.

African Union forces expelled al-Shabab from Mogadishu in August 2011, ending years of daily violence that had caused the rest of the world to shun the capital for two decades. After the ouster of al-Shabab, the international community started trickling back into the capital, and the United Nations began moving its personnel to Somalia from Kenya.

But the extremists of al-Shabab still hold sway in large parts of rural southern Somalia and retain the ability to stage lethal attacks even in Mogadishu. Last month, militants on a suicide mission invaded the U.N. compound in Mogadishu with a truck bomb and then poured inside, killing at least 13 people before dying in the assault.

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