The Obama administration confirmed Friday that a U.S. citizen took part in a suicide bombing in Syria, the first time that an American is believed to have done so in the three-year conflict there.

The American was identified as Moner Mohammad Abusalha, 22, of South Florida and of Middle Eastern descent. U.S. officials, who spoke on the condition of anonymity to discuss details of the investigation, said that Abusalha appears to have traveled to Syria more than once and that law enforcement had been aware of his trips to the region before he killed himself.

Reports that an American was involved in the suicide attack in the northern province of Idlib on Sunday surfaced online this week, with a video posted by Jabhat al-Nusra, a group linked to al-Qaeda, showing Abusalha packing a large truck with shells and purportedly driving toward their destination.

In the video footage, a massive explosion can then be seen in the Idlib countryside, alongside a picture of a bearded man believed to be Abusalha cradling a kitten. He is identified by his nom de guerre, Abu Huraira al-Amriki, “the American.”

A statement by Jabhat al-Nusra said the attack was one of four coordinated suicide bombings against government positions, in which two other foreign fighters and a Syrian participated.

Abu Huraira al-Amriki is identified as the man shown in a massive explosion in the Syrian countryside.

Dozens of Americans have traveled to Syria since the conflict there started, raising concerns that some could return to the United States to launch attacks. Preventing that outcome has become one of the FBI’s top counterterrorism priorities, and officials have charged several people with attempting to support terrorism in Syria.

On Friday, law enforcement officials said they had been in contact with Abusalha’s family. His identity was first reported on the Web site of the New York Times.

Orlando Taylor, 25, said he was close friends with Abusalha’s older brother, Mahrous, in Vero Beach, Fla., where Abusalha’s parents still live. Taylor said he knew Abusalha and considered him a peaceful, deeply religious figure.

“Moner was a real activist. He was a full Muslim,” Taylor said in a telephone interview. He said Abusalha attended Sebastian River High School, quit before graduating but then went on to earn his equivalency around 2008. Taylor said that he attended a service at a mosque in Orlando once with the younger Abusalha and that Abusalha would travel to take part in religious events, including “fast festivals,” where participants go without eating for days.

“He spoke in tongues. He sang the Koran and all that,” Taylor said. Even so, Taylor said, Abusalha never expressed violent or extremist views. “Honestly, he was just a regular person,” Taylor said. “He was one of the nicest people I knew. I never saw any weird side to him. Very respectful. He was definitely into his religion.”

Public records show that Abusalha’s family has owned several grocery stores in the Vero Beach area. His father and mother also own a grocery store in Melbourne, Fla. His father, through an employee at the store, declined to comment Friday night.

Bill Miller, a onetime Vero Beach neighbor, said that Abusalha’s family lost their home to foreclosure in 2009 or 2010, and later moved to the rental home where they live now.

Miller said Abusalha used to play basketball with his son.

He recalled one instance when Abusalha got suspended from school after fighting with some boys. The boys had made fun of his mother who wore the burqa when she came to pick him up from school.

Later, Miller said, his children reduced contact with Abusalha after he moved to Orlando and was attending the University of Central Florida because of his Facebook posts — “a lot of it was just him being angry and him going out and partying and having a really good time.”

“I said that didn’t make sense,” Miller said, “because if you’re very religious, you’re not supposed to be doing those things.”

A Facebook page that appeared to belong to Abusalha included a picture of him smiling in Miami Beach. Among his Facebook “likes” was the game “Call of Duty,” along with Dunkin’ Donuts and Cheetos.

But there were also signs of his religiosity. In 2011, for instance, he wrote: “Dear Allah, You are my Lord and I am your slave. I regret all my sins and ask you for forgiveness.”

Abusalha also lived in Fort Pierce, Fla., 130 miles north of Miami. A neighbor in the apartment complex where he and other family members lived said they moved away shortly after 2000.

Several Americans have died during the conflict in Syria, but no other U.S. citizen is known to have staged a suicide attack.

FBI Director James B. Comey said this month that officials are determined to prevent what happened in Afghanistan before the Sept. 11, 2001, attacks, when jihadists traveled to the region unfettered in the 1980s and 1990s.

“We see Syria as that, but an order of magnitude worse in a couple of respects,” he told reporters. “Far more people going there. Far easier to travel to and back from. So, there’s going to be a diaspora out of Syria at some point, and we are determined not to let lines be drawn from Syria today to a future 9/11.”

Rebel attacks in Syria come amid a big offensive in the province of Idlib that has produced some significant gains, fueled by an influx of weapons including, for the first time, American TOW antitank missiles. This week, the rebels captured the strategically significant town of Khan Sheikhoun, which straddles the main highway linking northern and central Syria, one of their most important advances in months.

The rebels are threatening an offensive against the provincial capital of Idlib, which has remained in government hands since the beginning of the war. Thousands of civilians have fled the town in recent days to escape the anticipated fighting.

Rodriguez reported from Melbourne, Fla. Julie Tate and Anne Gearan in Washington and Liz Sly in Beirut contributed to this report.