Seven civilians were killed and nine wounded after a mortar shell was fired into a crowded neighborhood of the Somali capital Mogadishu, official and witnesses said Tuesday. It was not immediately clear who was behind the shelling late Monday, the latest in a string of attacks in the anarchic capital, where diehard al-Qaeda allied al-Shabaab insurgents have launched guerrilla assaults on the government. “Seven people were killed and nine others injured, it was a disaster that shocked everyone,” said Dahir Adan, a witness. Somali security officials confirmed the attack and said they were investigating. The Islamist al-Shabaab abandoned most of their fixed positions in Mogadishu in August, but have vowed to continue to battle the Western-backed government, who are protected by an 11,000 strong African Union force.