A car bomb has exploded near a government convoy in the Somali capital Mogadishu, killing at least eight people, officials say.
A police spokesman told AFP news agency a suicide attacker had driven a car laden with explosives at an armoured government vehicle.
According to the same source, those inside the vehicle survived the blast.
The attack comes just days before a major conference in London on the future of Somalia.
No group said immediately it had carried out Sunday's attack.
The country's main Islamist group al-Shabab, which is part of al-Qaeda, has been forced out of the main cities in the south and centre but still controls smaller towns and many rural areas.
Five people were also injured by the explosion, a local official told Reuters news agency.
One of the agency's photographers said he could see three people lying motionless near the wreckage of four burning cars.
The London conference will discuss how best the international community can support Somalia's progress.
More than 50 countries and organisations are due to take part when it opens on Tuesday, co-hosted by Somali President Hassan Sheikh Mohamud and UK Prime Minister David Cameron.
The UK recently re-opened its embassy in Mogadishu.
The security situation in city was thought to have been improving after two decades of conflict, despite occasional attacks.
Masked gunmen shot dead the deputy chief prosecutor, Ahmad Shaykh Nur Maalin, last month in the city centre.