WASHINGTON — A U.S. military official says the American-backed Syrian Democratic Forces captured two British members of an Islamic State insurgent cell commonly dubbed “The Beatles” and known for beheading hostages.

The official says that El Shafee Elsheikh and Alexanda Amon Kotey were captured in January in Syria. The two men are among four members of the IS cell that captured and beheaded more than two dozen hostages including American journalists James Foley and Steven Sotloff, and American aid worker Peter Kassig. The official spoke on condition of anonymity to provide details of the Syrian capture.

The State Department imposed sanctions on both men. They are believed to be linked to the British terrorist known as Jihadi John, the masked IS militant who appeared in videos showing the beheadings of Western hostages.