Two American citizens fighting for ISIS have been apprehended in Syria after Syrian Democratic Forces (SDF) special operations units raided an Islamic State compound near the Syria-Iraq border on Sunday. Warren Christopher Clark, a 34-year-old originally from Texas who goes by the name Abu Muhammad al-Ameriki, was arrested along with another American expat—Zaid Abed al-Hamed, 35—after U.S.-backed forces discovered the militant group was preparing to launch terrorist attacks against Syrian civilians in the area. In addition to the two Americans, the SDF also captured two fighters from Pakistan and one from Ireland.

“The incident is under investigation,” said U.S. Army Col. Scott Rawlinson, spokesman for Combined Joint Task Force Operation Inherent Resolve (CJTF-OIR), according to a report from Stars and Stripes.