BERLIN (AP) — German authorities have arrested four Iraqis suspected of membership in the Islamic State group, including one who is alleged to have carried out attacks that killed and wounded U.S. troops.

Federal prosecutors say the men were arrested Wednesday in the towns of the western cities of Dortmund and Bottrop, and Amberg-Sulzbach county in Bavaria.

In a statement Thursday, prosecutors said 27-year-old Mohammed Rafea Yaseen Y. is suspected of joining the Islamic State of Iraq group in his hometown of al-Rutba in 2006. He allegedly helped make improvised explosive devices used in 12 attacks. Prosecutors say U.S. troops were killed or wounded in the first 10 attacks, while Iraqi security forces and civilians were killed in the other two.

All four left Iraq in mid-2015 and entered Germany soon after.