A young boy is carried to hospital in Mogadishu following a mortar exchange between Islamist insurgents and Africa Union troops. (Abdurashid Abdulle/AFP/Getty Images)
Hospital sources said at least seven more people died in artillery battles that broke out after the blasts. A Somali government source said a senior officer of the AU force AMISOM was among the dead and its commander was slightly wounded.
Just days after the insurgents had vowed to avenge this week's killing of a top al Qaeda suspect by U.S. commandos, witness Farah Hassan said two U.N.-marked vehicles drove into the base followed by two pick-ups carrying government troops.
"We thought they were real U.N. cars carrying white people, but moments later deafening thunder shook the ground," he told Reuters. "The area was covered with flames and clouds of smoke."
A Reuters reporter had earlier seen six wounded soldiers carried away from the site of the explosions, some bleeding heavily, while thick smoke poured into the sky over the capital.
Among the dead were some Somalis who had been receiving medical treatment at the heavily-guarded AU base, witnesses said. Somali government officials were meeting representatives of the African Union peacekeeping mission there at the time.
It looked to be the worst attack on the 5,000-strong force since 11 Burundians were killed and 28 wounded in February by two suicide bombers who infiltrated another base.
It also followed one of the most violent months the city has seen in 20 years.
A suicide bomber killed Somalia's national security minister and at least 30 other people in a June strike on a central town, again targeting high-level officials attending a meeting.
Fighting in Somalia has killed more than 18,000 civilians since the start of 2007 and left another 1.5 million homeless.
‘We Got Our Revenge’
Western security agencies say lawless Somalia has become a safe haven for militants, including foreign jihadists, who are using it to plot attacks across the region and beyond.Al Shabaab's spokesman, Sheikh Ali Mohamud Rage, told Reuters Thursday's attacks were to avenge the death of Kenyan-born Salah Ali Saleh Nabhan, who was killed in southern Somalia on Monday in a raid by U.S. special forces.
"We have got our revenge for our brother Nabhan. Two suicide car bombs targeting the AU base, praise Allah," he said, adding there were five suicide bombers in the two cars.
"It took place at noon on the 27th of Ramadan, the best blessing. We knew the infidel government and AU troops planned to attack us after the holy month. This is a message to them."
Nabhan, 28, had been allied with al Shabaab, which Washington accuses of being al Qaeda's proxy in Somalia.
Thursday's attack may deter some African nations, including Nigeria and Djibouti, that have agreed in principle to send soldiers to reinforce the AU mission. So far, Uganda and Burundi are the only nations to have sent soldiers.
Jean Ping, chairman of the AU Commission, said "a number" of peacekeepers had been killed and many others wounded.
"This terrorist attack is further testimony of the continued threat posed by the elements opposed to peace and stability ... and by their backers, within and outside Somalia," Ping said.
Hours before the suicide attacks, al Shabaab had issued demands in return for the release of a French security consultant the rebels are holding, including an immediate end to French support for Somalia's fragile government.
The French hostage is one of two security consultants kidnapped by gunmen in Mogadishu in July. His colleague escaped on Aug. 26.
Al Shabaab demanded the "immediate cessation of any political or military support to the apostate government of Somalia and the withdrawal of all its security advisers in Somalia", the rebels said in a statement.
They demanded the withdrawal of the AU troops supporting President Sheikh Sharif Ahmed's administration and the departure of French warships trying to stamp out piracy in Somali waters.
The insurgents' statement also called for the release of mujahideen prisoners in other countries.
