At least six people have been killed after a suicide bomber blew himself up among a group of security officials outside the Somalian prime minister's office, army officials say.
It is believed that many of those killed or wounded in Tuesday's bombing in Mogadishu were soldiers or police.
"I saw the dead bodies of six people and several others were injured," Abdukadir Ali, a Somali military official who stayed near the scene of the attack in central Mogadishu, said on Tuesday.
"The bomber was sitting near a perimeter wall and detonated himself in the midst of a group of security forces.
"There was chaos, smoke and pieces of human flesh."
Abdi Farah Shirdon Said, Somali prime minister, was in his office at the time when the attacker struck, officials in his office said, but he was not harmed by the blast.
"The area was closed down by the security forces. I saw several dead soldiers and others injured being rushed to hospital," Mohamed Hussein, a witness, said.
Al-Shabab has conducted a series of guerrilla-style attacks in the Somali capital.
The fighters have vowed to topple Hassan Sheikh Mohamud, the newly elected president who took office in September after being chosen by the country's new parliament, bringing an end to eight years of transitional rule.
Al-Shabab fighters are on the back foot, having fled a string of vital towns ahead of a 17,000-strong African Union force, which is fighting alongside Somali government troops to wrest territory off the armed group.