(CNN) - The Department of Defense has identified three of the four Americans killed in Syria on Wednesday.
Army Chief Warrant Officer 2 Jonathan R. Farmer, 37, of Boynton Beach, Florida; Navy Chief Cryptologic Technician Shannon M. Kent, 35, of upstate New York; and DOD civilian Scott A. Wirtz of St. Louis, Missouri were killed Wednesday in the explosion in Manbij, Syria, according to the Department of Defense.
All three died "as a result of wounds sustained from a suicide improvised explosive device," according to the military.
The fourth American killed in Syria was a contractor supporting the Defense Department, according to a Pentagon spokesman. The Pentagon will not release his name since he was not military.
Kent was a sailor assigned to Cryptologic Warfare Activity 66, based at Fort George G. Meade, Maryland. Farmer served on six overseas combat tours and was a decorated soldier awarded the Bronze Star and the Purple Heart.
Wirtz, a former US Navy SEAL, was an intelligence expert in Syria with the troops hoping to collect information about security and adversaries in the area.
The bombing is still under investigation.
CNN reported Thursday that the US initial assessment is that ISIS is responsible for the bombing.
The explosion in the northern city of Manbij Wednesday killed the four Americans and at least 10 other people. Eight civilians and two fighters from the US-backed Syrian Democratic Forces were killed in the blast, a senior commander from the Manbij military council told CNN.
The US-led coalition Operation Inherent Resolve said Wednesday that the service members were "conducting a routine patrol" at the time of the explosion. Three other US service members were injured in the attack.
The attack came less than a month after President Donald Trump announced that US troops would withdraw from Syria.
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