The Obama administration is investigating reports from Syria that a second American was killed over the weekend while fighting alongside Islamist State (IS, formerly ISIS) extremists, USA Today reported Wednesday.
The news comes a day after U.S. officials confirmed that 33-year-old Douglas McCain, who had lived in Southern California and Minnesota, died in a battle between the Islamic State and other Syrian opposition groups.
The other American was not identified.
NBC News cited a Free Syrian Army source as saying another American jihadist fighting with the Islamic State also was killed. NBC also quoted an unnamed law enforcement source as saying the report of the second American's death "appears to be true" but offered no details.
The National Security Council said in a statement Wednesday evening that it was "aware of media reporting and social media activity indicating that a 2nd American citizen associated with" the Islamic State had been killed in Syria.
"At this point, we are not in a position to confirm those reports," it said, according to USA Today.
These incidents highlight the West’s concerns about citizens traveling to the Middle East to fight alongside jihadist groups.
In February it was estimated that at least 50 U.S. citizens are fighting in Syria, and are liable to bring terrorism back to their home country once the war is over.
The State Department estimates there are about 12,000 foreign fighters from at least 50 countries in Syria.
There are also Russians, Germans, Canadians and French citizens taking part in the fighting in Syria.