Story highlights An estimated 300 US Special Forces are currently operating in Syria

Four US service members have been killed in Iraq fighting ISIS

(CNN) A US service member was killed in northern Syria Thursday from wounds sustained in a blast from an improvised explosive device, according to the US-led coalition fighting ISIS.

This marks the first time a US service member has been killed inside Syria since a small number of US Special Forces were sent there last year to advise and assist Syrian forces battling ISIS, also known as ISIL.

"The entire counter-ISIL coaltion sends our condolences to this hero's family, friends and teammates," Lt. Gen. Stephen J. Townsend, commander of Combined Joint Task Force for Operation Inherent Resolve, said in a statement.

It is customary for the US military to wait at least 24 hours before identifying casualties to allow for next of kin notification.

The incident occurred in the vicinity of Ayn Issa, some 30 miles north of ISIS's self-declared capital of Raqaa. Defense Secretary Ash Carter and other top defense officials have said operations to retake the city from ISIS would begin in the near term, as the battle against ISIS in its Iraqi stronghold of Mosul is already underway.

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