A car bomb rammed into a cafe in the Somali capital Mogadishu near compounds housing government ministries on Wednesday, killing seven people, officials and ambulance services said.

Reuters witnesses said the blast destroyed the cafe and damaged another one. Three cars were destroyed and blood stained the floor. Smoke billowed from the scene.

"So far we have carried seven dead people from the blast. Casualties may rise," Abdikadir Abdirahman, the director of Amin ambulances, told Reuters.

Police said the blast took place near the compounds housing the security and sports ministries.

The incident occurred after the new security minister, Mahamed Abuukar Islow, took office and promised he would come up with a plan to tighten security.

Police had earlier put the number of dead at three.

"We have confirmed seven civilians were killed in the blast by al Shabaab," Abdifatah Omar Halane, spokesman for Mogadishu's mayor, told reporters at the scene.

Al Shabaab were not immediately reachable for comment. In the past, have taken responsibility for blasts and gun attacks in the capital and elsewhere in Somalia.