A man who blew himself up in an attack that killed at least 10 people in Somalia on Saturday may have been a U.S. citizen from Minneapolis who returned to Somalia three years ago, several Minnesotans with Somali ties said on Sunday.

Before the attack, the man made an audiotape posted by the Somali militant group Al-Shabab in which he urged other young people not to "just chill all day" and to instead fight nonbelievers. The website Somalimemo.net posted the tape, saying the bomber, whom Al-Shabab identified as Somali-American Abdisalan Taqabalahullaah, emigrated to the United States when he was 2.

In Minneapolis, Omar Jamal, first secretary of the Somali mission to the United Nations, said on Sunday that he has heard from five community members who listened to the tape and identified the bomber as Abdisalan Ali, 22, a Minnesotan missing since fall 2008 whose nickname was "Bullethead."

Jamal said Ali graduated from Edison High School in Minneapolis, where he lifted weights and sold shoes out of his locker to make money to support his family, which still lives in northeast Minneapolis. He also attended the University of Minnesota for a time.

If authorities verify his identity, he would become the third identified Minnesotan to have died as a suicide bomber in Somalia. About 20 young men from Minnesota are thought to have traveled to that war-torn nation in the past few years to join the fighting, and Ali's death would mark the 10th death of a Minnesotan there.

Jamal said he heard the audiotape by the man, whom he says came to Minneapolis as a young child and returned to Somalia, where he married. He said Ali's parents, whom he declined to identify, have said they don't want to comment on the suicide bombing.

Uncertainty on ID

There was uncertainty in the community over the identity of the man on the audiotape. Minnesota Public Radio reported that three unnamed friends of Ali do not believe it's him.

But others disagree. One of the five people who told Jamal he believes the taped voice was Ali's was Osman Ahmed, president of Minneapolis' Riverside Plaza Tenant Association.

Ahmed said he met Ali, then a University of Minnesota student, at the high school graduation of a mutual friend more than three years ago. Ahmed said Voice of America, which broadcasts news in Somali and other languages, asked him to listen to the tape and try to identify the speaker.

"Immediately, I recognized his voice," said Ahmed, who has testified at congressional hearings about Al-Shabab's recruiting of American Somalis.

Ahmed said he went to the home of Ali's mother and found neighbors who said she had been very upset. He said the family told him that Ali last called his family six months ago to say he and his wife were expecting a baby.

Abdirizak Bihi, another Somali community activist in Minneapolis, said he knows two friends of Ali who listened to the audiotape and believe it is Ali. Bihi said he hoped to meet with Ali's mother, who had been in a support group with Bihi. Bihi lost a nephew, Burhan Hassan, 18, to violence in Somalia.

As in previous such cases, there was no ready confirmation coming from the FBI, which has investigated the cases of young Minnesotans who have gone to Somalia.

Agent E.K. Wilson said on Sunday that the agency was well aware of reports that an American was involved in Saturday's suicide bombing.

Wilson, who supervises Operation Rhino, which has investigated the exodus to Somalia, said he knew of Abdisalan Ali, who left Minneapolis in fall 2008 with other young Somalis. "We are not able to make any confirmation yet that it is this guy," he said. "We are actively looking into it. He is an Operation Rhino subject."

Wilson said his agents have heard the audiotape. "We are looking at that and every other piece of information we can get our hands on to determine credibility," he said. "We have seen this before -- martyrdom video or audiotapes. I can't say yet if the audiotape is credible."

Wilson said that if Ali proves to be the bomber, he would be the third suicide bomber from Minneapolis. The first was Shirwa Ahmed, who died in October 2008. The second was Farah Mohamed Beledi, killed in June of this year in an attack in Mogadishu.

'A very convincing guy'

The young man in the audiotape has an American accent and mixes Muslim terminology with American slang as he urges Muslims to carry out attacks against non-Muslims.

"My brothers and sisters, do jihad in America, do jihad in Canada, do jihad in England, anywhere in Europe, in Asia, in Africa, in China, in Australia," the voice says. "Anywhere you find [unbelievers], fight them and be firm against them.

"Today jihad is what is most important thing for the Muslim ummah," he says, using a word for the Islamic community. "It is not important that you, you know, you become a doctor or you become, you know, uh, some sort of engineer.

"We have to believe in Allah and die as Muslims," he says. "Brainstorm, don't, don't just sit around and, you know, be, be be a couch potato and you know, you know, just like, you know, just chill all day, you know. It doesn't, it doesn't, it will not benefit you, it will not benefit yourself, or the Muslims."

Bihi said the man speaking on the tape is "a very convincing guy" in his appeal for Somalis everywhere to join Al-Shabab. "I am worried about the tape getting into the community," Bihi said. "It would be a very good tool for [Al-Shabab] recruiters here in America. It scared the hell out of me, how good it is."

More carnage in Mogadishu

In Saturday's attack at an African Union base in Mogadishu, two suicide bombers blew themselves up, killing from 10 to 13 people, according to witnesses cited by various news outlets.

About 9,000 African Union peacekeepers supporting Somali government troops have almost pushed Al-Shabab out of Mogadishu. Earlier this month, Kenya opened a second front, sending soldiers into southern Somalia.

The insurgency is outgunned and has been weakened by a famine in its strongholds. But it still maintains the ability to carry off major attacks such as Saturday's two-hour assault on the African Union base.

Somalia has not had a functioning government in more than 20 years.

Jim Adams • 952-746-3283 The Associated Press and New York Times contributed to this report.