MOGADISHU - At least two people were killed and 8 others wounded after mortar rounds fired by Somalia's al Shabaab rebels towards the presidential palace landed on a nearby camp for the internally displaced, witnesses and officials said on Monday.Under pressure from African Union and Somali government troops, the al-Qaida-linked militants withdrew from Mogadishu in August prompting a return to relative calm in the capital, although they still manage to launch sporadic attacks.Paddy Ankunda, spokesman for the African Union force known as AMISOM, said some mortars hit a camp for Somalis displaced by war and famine about 300 meters from the presidential palace.Ismail Nur, a resident of the camp, said one mortar killed two members of a single family."A mortar landed on our camp - a father and his son died. Eight others including three women were injured," Nur, who is a nephew to the dead father told Reuters.Al Shabaab said they fired mortars at the heavily protected presidential compound, their third attempt to strike at the heart of the government in a fortnight.