(CNN) American citizen Keith Broomfield was killed fighting in Syria, a State Department official confirmed Wednesday.

The official said the State Department was in touch with Broomfield's family.

Jennifer Broomfield, a woman who identified herself on Facebook as Keith Broomfield's sister, shared an image of a text message conversation on the social medium, which she said were the "Last words I had with my brother."

"My unspoken prayers and tears for those in the Middle East were answered when he left to fight," she wrote. "I didn't think I would lose him."

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