Two large explosions followed by gunfire have been heard near the presidential palace in Somalia's capital.
The blasts come a week after a similar attack on the interior ministry compound in Mogadishu killed at least nine people.
The Somalia-based al-Shabab extremist group, an arm of al-Qaida, often targets high-profile places in the capital and claimed responsibility for the attack a week ago.
The threat from what has become the deadliest Islamic extremist group in sub-Saharan Africa has hurt efforts to strengthen Somalia's fragile government and stabilise the long-chaotic Horn of Africa nation.