MOGADISHU, Somalia - Islamic insurgents posing as U.N. personnel detonated suicide car bombs in an African Union peacekeeping base yesterday to avenge a U.S. commando raid that killed an al-Qaeda operative.

Witnesses and officials said the bombings and a counterstrike from the AU base killed at least 16 people, including four bombers, and injured dozens, including one American.

The sophisticated suicide attack underscored links between al-Qaeda's terror network and Somalia's homegrown insurgency. Many fear this impoverished and lawless nation is becoming a haven for al-Qaeda.

An hour after the bomb attack, there was more bloodshed. Missiles fired from the peacekeepers' airport base exploded in insurgent-controlled areas of the capital.

An Associated Press photographer saw a young woman and a girl dead on the street, their bodies bloodied from their wounds.

Ali Muse of the Mogadishu ambulance service said the missiles killed seven people and wounded 16.

The suicide bombings are a hallmark of al-Qaeda that can be traced to training from extremists like the operative killed this week by helicopter-borne U.S. special forces, said Ted Dagne, a Washington-based Africa specialist.

Suicide attacks were virtually unknown in Somalia before 2007, even though the nation has been wracked by war for almost two decades.

"Al-Qaeda provided the training as well as the brainwashing," Dagne said.

Al-Shabab, a powerful Islamist group with foreign fighters in its ranks, controls much of Somalia and operates openly in the capital, confining the government and peacekeepers to a few blocks of the city. The United States and the United Nations support Somalia's government and the African peacekeeping force.

The suicide bombers arrived at the airport in U.N. cars packed with explosives and drove onto the main base of the AU peacekeepers before setting off two huge blasts that shattered windows over a wide area and shrouded the sky in black smoke.

An airport security officer said soldiers guarding the base waved in the trucks because they were U.N. vehicles. Prime Minister Omar Abdirashid Ali Sharmarke confirmed the cars were stolen.

A witness, who spoke on condition of anonymity for fear of reprisal, said there were 11 bodies at the AU base. But the AU said nine people were killed there: four suicide bombers and five officials from the Somalian government and the AU force, including its Burundian deputy commander.

At least one American was wounded by the bombings, according to a police official in Nairobi, Kenya, where several of the wounded were flown.

Al-Shabab claimed responsibility for the bombings and said the attack was in retaliation for the death of Saleh Ali Saleh Nabhan.

Nabhan was killed Monday in southern Somalia by U.S. special forces who blasted his vehicle with machine-gun fire from helicopters.