The attacks took place at a hotel in the capital.
A police official said a former lawmaker and a police official were among those killed in the attack.
A car bomb had targetted the Nasa-hablood hotel near the presidential palace, soon after another car bomb exploded near the scene, the official added.
"The first attack was caused by a suicide car bomber targetting the Nasa-hablood hotel. At least 10 people were killed, more than eight others wounded," Police Officer Ali Mohamed said, adding, "the second car bomb exploded 30 minutes later near the National Intelligence Agency prison known as Godka-jilacow."
The Somali-based insurgent group, al-Shabaab, claimed responsibility for the attack.
Earlier this month, more than 300 people were killed in the massive twin truck bombings in Somalia's capital.