WASHINGTON (AP) — The Pentagon has identified three of the four Americans killed in a suicide bomb attack claimed by the Islamic State group in Syria this week.

They are Army Chief Warrant Officer 2 Jonathan R. Farmer, 37, of Boynton Beach, Florida, who was based at Fort Campbell, Kentucky; Navy Chief Cryptologic Technician (Interpretive) Shannon M. Kent, 35, from upstate New York and based at Fort Meade, Maryland; and a civilian, Scott A. Wirtz, from St. Louis.

The Pentagon hasn’t identified the fourth casualty, a civilian contractor. The four were killed in the northern Syrian town of Manbij on Wednesday. The attack also wounded three U.S. troops and was the deadliest assault on U.S. troops in Syria since American forces went into the country in 2015.