A suicide car bomber targeting a convoy of Qatari officials in central Mogadishu has reportedly killing eight Somalis.
The delegation, travelling through the Somali capital in the interior minister's bullet-proof vehicle, were "safe", a security officer told Reuters.
The Al Shabaab Islamist rebel group claimed responsibility for the attack, telling Reuters by phone that "more explosions are on the way."
Al Shabaab has stepped up attacks on Somalia's government, which it considers a "puppet" of Western powers.
The Al Qaeda-linked group also controlled most of Mogadishu until the military pushed the militants out of the capital two years ago.
However, Somalia's frail African Union-backed transitional government has needed peacekeepers to stay on top of the fight against Islamist guerrillas for years.
One of the worst recent attacks occurred last month, when at least 10 heavily armed militants forced their way into a court building in Mogadishu, killing 29 people.
EuroNews reported that Sunday's "massive" blast killed several officials.
However, CNN cited the African Union command in Mogadishu as saying that at least seven civilians were killed in the attack.
CNN cited Somali President Hassan Sheikh Mohamud as saying that the uptick in violence was "nothing but a sign of desperation by the terrorists" who "are in complete decline."