EDS NOTE GRAPHIC CONTENT Rescuers carry away a wounded civilian following a blast outside a district headquarters in the capital Mogadishu, Somalia, Monday, Sept. 10, 2018. A number of people are dead after a suicide bomber detonated an explosives-laden vehicle at the gate of the Hodan district headquarters in Mogadishu, according to police. (AP Photo/Farah Abdi Warsameh)

NAIROBI — Six people were killed and another 16 injured when a car bomb exploded outside a local government office in Mogadishu on Monday, Somali police and rescue workers said.

"Our ambulance teams have collected the dead bodies of six people," said Abdiqadir Abdirahman, director of the city's Aamin Ambulance service.

He said 16 others were wounded in the blast. 

Police officer Ibrahim Mohamed said a vehicle had rammed a security checkpoint outside the Hodan district headquarters then exploded. 

"The blast was huge," he said.

The explosion levelled buildings and left a thick plume of smoke which could be seen across the city.

"It caused a huge blast and there was dust everywhere," said Osman Ali, who was in the area at the time.

Images from the scene showed collapsed buildings -- including a mosque -- with rescue workers and civilians picking through the debris.

Nur Adan, a bystander, told AFP he saw "several dead bodies being recovered from under wreckage" and that the blast had destroyed two local mosques. 

The attack was claimed by the Shabaab, an al-Qaeda aligned jihadist group fighting to overthrow the internationally-backed government in Somalia.

Active for the last decade, the militants carry out regular bombings and armed assaults on government, military and civilian targets in the capital.