MOGADISHU (REUTERS) - At least four people were killed on Tuesday (March 21) when a car bomb exploded at a checkpoint less than a kilometre away from the presidential compound in Somalia's capital, Mogadishu, police said.

Security officials at the scene told Reuters the checkpoint was rammed by a car bomb driven by a suicide attacker, causing a blast outside a theatre.

"At least four people, including government soldiers and civilians, died in the blast. Several others were injured," said Mohamed Hussein, a police officer.

"Casualty numbers may rise. There were pedestrians along the street at the time of the explosion," he told Reuters.

The theatre is about 300 metres away from the heavily fortified compound known as Villa Somalia, which also houses other government agencies.

It was not immediately clear who was responsible for the explosion. In the past, al Qaeda-linked al Shabaab has taken responsibility for blasts and gun attacks in the capital.

Al Shabaab has been able to carry out deadly bombings despite losing most of its territory to African Union peacekeepers supporting the Somali government.

The group's insurgency aims to drive out the peacekeepers, topple Somalia's western-backed government and impose its strict version of Islam on the Horn of Africa state.

Somalia swore in a new leader last month. Mohamed Abdullahi Mohamed has promised al Shabaab's fighters "a good life" if they surrender.