A 33-year-old San Diego man was killed over the weekend fighting for the Islamic State, NBC Newsis reporting.
NBC said it has seen photos of Douglas McAuthur McCain's passport and body -- which features a distinctive neck tattoo. NBC, citing an activist linked to the Free Syrian Army who also saw the photos, said McCain was among three foreigners fighting with ISIS who died in Syria.
The State Department is "aware of these reports" but could not confirm the death, spokeswoman Jen Psaki said, adding that officials are in contact with McCain's family.
"There's a process that needs to be gone through before any confirmation can be made and I won't have any more information at this time," she said.
CNN, however, reported that McCain's uncle said the State Department informed the family Monday of McCain's death.
NBC said it had contacted members of McCain's family and dozens of friends — including his mother, sister, aunts and cousins. A woman who said she was McCain's aunt confirmed that he had "passed" and referred calls to McCain's mother.
Islamic State, also called ISIS or ISIL, is waging a war aimed at building an arch-conservative Sunni state across a swath of Syria and Iraq. The group made global news last week with a video showing the beheading of American photojournalist James Foley.
President Obama then urged Muslim nations to band together to stop the Islamic State.
The Facebook page NBC says is McCain's indicated he went to Robbinsdale Cooper High School in New Hope, Minn. McCain was born in Chicago and worked in San Diego for "Dawah -- Calling to Allah," which describes itself as a non-profit dedicated to spreading the word about Islam and inviting people to join the faith.
He lists as a recently added friend Abu Qaqa Al Malayzi, whose own Facebook page says he works for the Islamic State and currently lives in Raqqah, Syria, the current headquarters of IS. Al Malayzi changed his profile photo Aug. 22 to a photo wearing a mask and cradling an AK-47.
There are many posters on McCain's own Facebook photo page with a Muslim theme, including an "I (heart) Allah." Another is called "Soldiers of Allah" and shows what appear to be desert warriors striding toward the light under the headline "They are coming back."
There are also playful entries on his Facebook page, noting that he is a fan of both the Chicago Bulls and comedian Dave Chapelle.
Much of the information on the Facebook page was stripped away sometime Wednesday.