Among those are Islamic groups such as the Ahfad al-Rasoul, al-Furqan and Tawheed brigades, the rebel officials and activists said.

NPR: Qatar Faces Backlash Among Rebel Groups In Syria

One or more operatives may be involved in the attack, including Fawaz Yahya al-Rabeei , also known as (AKA) Furqan. al-Rabeei is believed to be a Yemeni national born in Saudi Arabia in 1979.

CNN: FBI statement

Other al-Rabeei AKA's include Fawaz Yahia Hassan Aribii, Fawaz al-Rubai, Fawaz Yehia Hassan al-Rabie, Fawaz Yahya Hasan al-Rabi'i, Fawaz Yahya al-Ribi (al-Ruba'i, al-Rabia'i, al-Rabi'i), Forqan al-Tajiki, Furqan al-Tajiki, Furgan al-Tajiki, Furqan The Chechen, Faris al-Baraq, Sa'id, Musharraf, And Salem al-Farhan.

CNN: FBI statement