By Mark Hosenball
WASHINGTON, Aug 27 (Reuters) - The U.S. National Security Council on Wednesday said it was aware of media reports that a second American associated with Islamic State militant fighters had been killed in Syria, but it could not confirm the death.
The reports came a day after a U.S. official said Douglas McAuthur McCain, of the Minneapolis area, was suspected of fighting alongside militants who were trying to carve out their own state in Iraq and Syria, and that he had died there.
"We're aware of media reporting and social media activity indicating that a second American citizen associated with ISIL has been killed in Syria," said National Security Council spokeswoman Caitlin Hayden.
"At this point, we are not in a position to confirm those reports," she added.
U.S. officials also said on Wednesday the State Department was looking into the matter and that the initial reports originated with Twitter messages from the Free Syrian Army, an umbrella organization for Western-backed rebels.
Islamic State has declared a caliphate in the large territory it has seized in Syria and Iraq, to the alarm of the Baghdad government and its allies in the West.
Attorney General Eric Holder said in July dozens of Americans were among roughly 7,000 foreign fighters that U.S. intelligence agencies estimate to be operating in Syria, out of roughly 23,000 violent extremists.
A 22-year-old man from Florida carried out a suicide bombing in Syria's Idlib province in May. A Denver woman was arrested in July on suspicion of trying to fly to Syria to support insurgents, and two men in Texas were taken into custody on similar charges in June.
CBS News, citing unnamed family members and friends, reported the second American was also from the Minneapolis area. The U.S. citizen has not been named.
Troy Kastigar, a high school friend of McCain's, joined militant group al-Shabab in Somalia and in 2009 made a recruitment video for them before he was killed during fighting.
(Reporting by Mark Hosenball in Washington, D.C.; Writing by Eric M. Johnson; Editing by Jeremy Laurence)