American Jihadi Killed in Syria Fighting, White House Says

— -- A Chicago-born jihadist has been killed while fighting in Syria, the White House said today, purportedly for the terrorist group ISIS.

Douglas McAuthur McCain, a 33-year-old rapper, was among several ISIS militants the Free Syrian Army claimed on Twitter had been killed over the weekend in fighting for the ancient Syrian city of Aleppo. Caitlin Hayden, a spokesperson for the White House National Security Council, said the administration was “aware” McCain was in Syria and “can confirm” his death.

“We continue to use every tool we possess to disrupt and dissuade individuals from traveling abroad for violent jihad and to track and engage those who return,” Hayden said.

The McCain family had been notified of the death by the State Department Monday, CNN reported. Jen Psaki, a State Department spokesperson, declined to comment on the matter earlier today “out of respect for the family,” telling reporters, “There’s typically a process that needs to be gone through before any confirmation can be made.”

"I really don’t understand why and how and I have no words," says a Facebook post today by Delecia McCain, who identifies herself as McCain’s sister. "I never thought this will be the way we say goodbye… This is absolutely unreal to me I love you big brother."

ABC News Deep Dive: Who Is ISIS?

Could Money Have Saved James Foley?

'Apparent' That James Foley Executioner Is British, Intel Agencies Race to ID Killer

McCain was born in Chicago, spent many years in Minnesota before moving to San Diego, according to public records. More than a decade ago, McCain shared a Minnesota home address with a classmate, Troy Kastigar. A young man by the same name reportedly was killed in 2009 in Somalia while fighting with an al Qaeda group there.

“If you guys only knew how much fun we have over here – This is the real Disneyland. Come here and join us,” Kastigar said in a recruitment video for the terror group, al-Shabab, before his death. On Facebook in 2013, McCain paid tribute to Kastigar.

WATCH: Al-Shabab’s American Pipeline for Terrorism

A Twitter feed attributed to McCain says that he converted to Islam a decade ago, which he called it the “best thing that ever happened to [him].” In June, the account retweeted another ISIS supporter who said, “It takes a warrior to understand a warrior. Pray for ISIS.”

NBC News first reported McCain’s purported death in the conflict, citing the FSA as well as pictures posted on Twitter that appear to show McCain after he was killed. The FSA tweet claimed two Americans had been killed in the same bout of fighting, but the second American has not been identified.

McCain is not the first American to die in the brutal fighting in Syria. U.S. officials say Moner Mohammad Abu-Salha blew himself up in a coordinated suicide attack in Syria in May. Abu-Salha was reportedly fighting for al-Nusra, a rival rebel group to ISIS.

More troubling to U.S. officials, Abu-Salha was able to return to the U.S. for months after receiving training in Syria, before he went back to the front lines.

U.S. and European security officials have been sounding the alarm for months over their citizens traveling to the conflict in Syria and Iraq, receiving terror training and potentially returning home to wreak havoc. U.S. officials have estimated more than 12,000 foreign fighters have joined extremists groups in Syria, some 100 of them Americans.

ABC News' Mike Levine contributed to this report.

CLICK HERE to return to the ABC News Investigative Unit homepage.