Police said at least five people were killed and four wounded in a car bomb attack claimed by al Qaeda-linked group al Shabaab close to the president's residence in the Somali capital.
A second explosion followed nearby but the cause has yet to be determined, Major Mohamed Hussein told Reuters on Saturday.
Al Shabaab, in comments broadcast on its Radio Andalus, claimed responsibility for both blasts and said the second was also a car bomb targeting those who had responded to the first.
"The first suicide car bomb at the checkpoint killed five people mostly security soldiers. Four others were injured. Death toll may rise. It is too early to have details of second blast," Hussein said.
A Reuters witness at the scene of the second blast said he saw at least two bodies.
Ahmed Abdi, another police officer, said the car bomb exploded at a checkpoint some 400 metres from the president's residence.
Al Shabaab carries out frequent attacks in Mogadishu. Its members want to dislodge the government and impose its rule based on its own strict interpretation of Islam's sharia law.