A second explosion followed nearby. Al Shabaab, in comments broadcast on its Radio Andalus, claimed responsibility for both blasts and said the second was also a car bomb.
“The death toll has risen to 13 people including civilians and soldiers. Seventeen others were injured. The casualties are from the two blasts,” Major Mohamed Hussein, a police officer, told Reuters.
Among those killed were a journalist, two security personnel and a driver working for local station Universal TV, whose car was passing the checkpoint at which the first blast went off, another reporter working for the station said.
“My colleague Awil Dahir Salad died in the blast together with the driver and two security guards. They were killed by the first blast as they drove. May Allah rest their souls,” journalist Abdiasis Ibrahim who works for Universal TV, told Reuters.
Police had earlier said the first car bomb at the checkpoint killed five, mostly soldiers.
A Reuters witness at the scene of the second blast said he saw at least two bodies.
Ahmed Abdi, another police officer, said the first car bomb exploded at a checkpoint some 400 meters 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.
The group was forced from Mogadishu in 2011 but maintains a foothold in some regions. It has killed thousands of Somalis and hundreds of civilians across East Africa in a decade-long insurgency.
Two explosions have hit Somalia's capital, Mogadishu, killing at least six people, Al Jazeera reported citing local media.
The first car bomb detonated at a checkpoint near the national theatre, sending thick white smoke billowing into the sky, Dalsan TV reported.
The second explosion took place just minutes after, reportedly in the same area.
Images circulating on social media showed destroyed vehicles and debris littering the streets.
The explosions have shattered nearly a month of calm in Mogadishu, which is often the target of attacks by al-Shabab.
The al-Qaeda linked armed group, which has carried out several attacks in Somalia and neighbouring countries, is fighting to topple the Somali government and wants to impose a strict version of Islamic law in the Horn of Africa country.
The group used to control most parts of the country, but since 2010, the fighters have been removed from most major towns and cities.