NAIROBI, Kenya - An air strike hit a refugee camp in southern Somalia, killing at least five people and wounding 45, most of them children, an international aid agency said Monday. Kenya's military acknowledged carrying out an air raid but said it targeted only al-Shabab, an Islamist insurgent group in Somalia.

Details emerged, meanwhile, about an American-Somali man who al-Shabab said carried out a suicide attack Saturday against an African Union base in the Somali capital. Al-Shabab identified the man as Abdisalan Taqabalahullaah. Omar Jamal, first secretary of the Somali mission to the United Nations, identified the man as Abdisalan Hussein Ali of Minneapolis based on what he said were Ali's friends listening to an audiotape posted by al-Shabab.

Ali was 19 when he disappeared in 2008 from Minnesota, which has a large Somali-American community. In July 2010, he was indicted in the U.S. with several other men. Charges included conspiracy to provide material support to a foreign terrorist organization and conspiracy to kill, maim, kidnap and injure. FBI spokesman Kyle Loven in Minneapolis said the agency is conducting DNA testing on the bomber's remains to try to make a positive identification.

Accounts differed on who was to blame for civilian casualties from the Kenyan air strike, but al-Shabab used them to try to win more recruits. Kenyan military spokesman Maj. Emmanuel Chirchir blamed an al-Shabab fighter for the civilian deaths, saying he drove a burning truck of ammunition into the refugee camp in the town of Jilib where it exploded.

Chirchir said the Kenyan air force hit the truck on Sunday as it drove away from an al-Shabab training camp. He said 10 al-Shabab members were killed and 47 wounded in the attack, citing informers on the ground.

But Doctors Without Borders, also known as Medicines Sans Frontieres or MSF, said the aerial bombardment hit the camp for displaced people. MSF said it treated 52 wounded people. As of Monday morning, MSF confirmed five deaths and said it was still treating 45 wounded, 31 of them children. Seven other patients had been discharged after receiving treatment. The head of the MSF mission in Somalia, Gautam Chatterjee, said most of the wounded had shrapnel injuries.

Jilib town elder Ahmed Sheik Don said the planes hit a bus stop and a location near the camp before finally hitting a base of al-Shabab, an insurgent group linked to al Qaeda.

It was impossible to immediately reconcile the different versions. Either way, civilian casualties would be a public relations issue for Kenya and could turn ordinary Somalis against Kenya's military intervention in the lawless nation.

Residents said hundreds ran for cover Sunday as bombs exploded. The town's population has ballooned this year as about 1,500 families fled to the area amid a famine that has wracked the south. Residents reported that al-Shabab fighters were among the casualties.

Sheik Abukar Ali Aden, an al-Shabab official in southern Somalia, said the militants donated food to those affected by the airstrikes. Bearded men and masked fighters used megaphones to ask Somalis to join their militant group.

"I am urging all Muslims in the Jubba regions to raise their heads and defend themselves against the enemy massacring them," Aden said at a news conference in the southern port town of Kismayo. "Go! go to the front lines and make jihad with the Christian enemy."

Kenya sent troops across the border into Somalia in mid-October following cross-border kidnappings blamed on gunmen from southern Somalia.

Somali Prime Minister Abdiweli Mohamed Ali said his government is looking into the airstrike and reports of civilian deaths.

"If it has taken place then it is an unfortunate incident and we are sorry about that," Ali said during a press conference in Nairobi alongside Kenyan Prime Minister Raila Odinga.

Odinga added: "Our troops have not targeted civilians. It would be most unfortunate."

The UN representative for Somalia, Augustine P. Mahiga, said civilians must be protected during any party's military operations. He said the UN hopes that Kenya's push into southern Somalia will help gain access to famine victims.

"We think this in the end will contribute to the sum total of gaining more territory, greater security and therefore more access to the victims of famine and drought, especially in south-central Somalia," Mahiga said.

The Danish Refugee Council, meanwhile, said it has made its first contact with an American aid worker and her Danish colleague who were kidnapped last week in northern Somalia.

"It has been some very long days as we have been waiting for signs of life. It is truly a relief that we now have received the message that they are as well as possible their circumstances taken into consideration," said Ann Mary Olsen, the head of the Danish Refugee Council's International Department.

Olsen said the aid agency is appealing to traditional leaders and clan elders to help release the hostages.

Somalia has not had a functioning government since 1991. African Union troops have been engaged in fierce fighting in Mogadishu, Somalia's capital, to push al-Shabab fro its last base in the city. On Saturday, the Islamists launched an attack with two suicide bombers, killing at least 10 people.

Kenya's military said Monday that its forces on Sunday attacked three skiffs -- small boats. It said two skiffs were attacked Monday and that 18 "pirates" were killed. The military did not explain how it knows how many people were killed. No further details were given.

The military also said one of its soldiers during an al-Shabab attack in Tabda died while undergoing treatment.