– An American who blew himself up in an attack in Syria on Sunday has been identified by law enforcement officials as Moner Mohammad Abu-Salha, a man who grew up in Florida and traveled to Syria late last year.

The officials said they believed that Abu-Salha, who adopted the name Abu Huraira al-Amriki, used a large truck in helping to carry out the bombing in the northern province of Idlib, where he had traveled after spending two months in a training camp of the militant group the Nusra Front in Aleppo. The officials said they thought it was the first time an American had been involved in a suicide attack in Syria.

U.S. law enforcement and intelligence agencies made the identification without examining any remains. The size of the blast, which was shown on a video clip posted by the Nusra Front, led the authorities to believe that there is little left of the body.

Without the body, the agencies came to their conclusion after analyzing intelligence from human sources in Syria and in foreign governments, and information gleaned from interviews with family members and friends of the bomber in Florida.

A Facebook profile of a man with the same name has pictures that appear to be of the same person shown in photos on jihadist websites.

Abu-Salha had been among several dozen Americans on the radar of federal law enforcement officials because of past trips to Syria.

One senior law enforcement official said the authorities believed that the attack occurred during the second visit Abu-Salha made to Syria to fight alongside Islamist militants who are battling the government of President Bashar Assad. He had been in Syria since 2013, said officials who spoke on the condition of anonymity.

News of the suicide attack surfaced Tuesday in Twitter messages from the Nusra Front, an Islamist extremist group in Syria aligned with Al-Qaida.

U.S. officials have not officially made public the name of Abu-Salha, who was believed to have been in his 20s or 30s. But on Friday at a State Department briefing, a spokesman said that the bomber was a U.S. citizen. A photo on jihadist social media accounts this week showed a smiling young man, bearded and holding a cat, who was said to be the bomber.

Activists also posted a video said to show the attack in which rebels loaded what appeared to be tank shells into a large armored vehicle, and there is an explosion after the vehicle drives down the road.

A Syrian fighter from the Nusra Front recalled Abu-Salha, whom he knew only by his alias, as an Arab-American who spoke Arabic poorly.

“He was a generous, brave, tough man, always on the front lines in battles,” said the fighter, who identified himself as Abu Abdulrahman.

“When his turn came up” to carry out a suicide bombing, he “was very happy, because he will meet his God after that,” the man said via Facebook.

Intelligence and law enforcement officials said Friday that it was easy for U.S. citizens to get in and out of Syria, and that many had traveled there for humanitarian reasons, presenting a challenge in determining who might be planning to carry out terrorist attacks in the United States.

“It’s trying to identify those individuals who have violent intent,” said Andrew McCabe, a senior FBI official. “That, quite frankly, is not easy.”

McCabe said that Americans who had traveled to Syria came from diverse backgrounds and upbringings. “When you put them together, they look like America,” he said.