WASHINGTON — An American who blew himself up in an attack in Syria on Sunday has been identified by law enforcement officials as Moner Mohammad Abusalha, a man in his early 20s who grew up in Florida and traveled to Syria late last year.

The officials said they believed that Mr. Abusalha, who adopted the nom de guerre 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.

Mr. Abusalha’s identity was confirmed Friday night by the State Department. American law enforcement and intelligence agencies made the identification after analyzing intelligence from Syria and foreign governments, and information gleaned from interviews with family members and friends of the bomber in Florida, one official said.

The size of the blast, which was shown on a video clip posted online by the Nusra Front, has led the authorities to believe that it will be impossible to ever identify Mr. Abusalha’s remains.