The four dead were all members of the same family. The two youngsters and their grandmother were killed at once and their father died later of his wounds.
"A woman and two children from the same family were killed in the Wardhigley area and several others were wounded," said Somali police officer Ibrahim Mohamed who blamed "mortar blasts" for the deaths.
"Several rounds of mortar shells landed close to the palace striking civilian occupied houses," Mohamed added.
No group has so far claimed responsibility for the attack.
"I think the mortar shells were aimed at striking the palace as they have landed in a close by neighbourhood," said Abdukadir Suleiman, a witness. "It was disaster and it killed several civilians.
