At least seven people were killed and at least 10 wounded on Monday when a car bomb exploded near a heavily-guarded complex housing the offices of Somalia's president and its prime minister in Mogadishu, a government spokesman said.
There were no immediate reports of anyone attempting to enter the complex, and there was no claim of responsibility.
The al-Qaeda-affiliated Shebab have often used cars driven by suicide bombers as a way of breaking into a location, with more attackers following on foot.
But this did not occur following Monday's attack, officials said.
“At least seven people were killed and more than ten injured” in the explosion, said Abdifatah Halane, government spokesman for the Banadir region which includes the capital.
“The majority of the dead and injured were civilians,” he added.
Earlier, Somali security official Ahmed Dahir put the death toll at five with with 13 injured, adding all were civilians.
“It was a car bomb but their target is not clear,” Dahir said.
Dahir said the device exploded near the checkpoint at the entrance to Villa Somalia.
“The explosion occurred between the main entrance of (Villa Somalia) and a nearby hotel,” said a witness called Ali Ahmed.
“I saw clouds of smoke up in the sky, it was very heavy.”
Expelled from Mogadishu in mid-2011, the Shabaab still hold large swathes of the countryside which they use as launching pads for their attacks.
They are fighting to overthrow the internationally-backed government in Mogadishu, which is protected by 22,000 African Union AMISOM troops from Burundi, Djibouti, Ethiopia, Kenya and Uganda.
The last attacks by suspected Shebab militants were on August 22.
In the first, a suicide bomber drove a vehicle laden with explosives into a base on the outskirts of the southern city of Kismayo, where African Union peacekeepers from Kenya as well as Somali government soldiers are stationed. Fourteen soldiers were killed.
In a second attack the same day, four civilians died when a car bomb went off near a police station in Mogadishu.
Recent months also saw the Shabaab overrun AMISOM bases home to Ugandan and Burundian troops outside Mogadishu,killing an unspecified number of soldiers in the process.
AMISOM did not give a casualties toll for either raid but witnesses spoke of dozens of fatalities in both cases.