An American citizen carried out a suicide bombing in Syria on behalf of an al Qaeda-linked militant group on Sunday, apparently the first time a U.S. citizen has carried out such an attack in the Syrian civil war, U.S. law enforcement and counterterrorism officials tell NBC News.

The officials, speaking on condition of anonymity, confirmed the suicide bombing and said they have identified the American. They declined to release his identity or hometown.

Word of the American’s death in the suicide bombing first surfaced Tuesday in tweets from the al-Nusra Front, an al Qaeda-linked group fighting the government of Syrian President Bashar Assad.

The tweets identified the bomber only by his Arabic nom de guerre, “Abu Hurayra al-Amriki,” (Abu Hurayra the American) and said he carried out one of four suicide bombings of Syrian government sites in Jabal al-Arbaa’in in Idlib Province — the scene of heavy fighting in recent weeks and months.