Hallel Yaffa Ariel, the 13-year-old Israeli girl who was stabbed to death by a Palestinian in her West Bank home on Thursday morning was a U.S. citizen, the State Department confirmed.

Ariel was sleeping when the Palestinian assailant, identified as Mohammed Tra'ayra, 19, broke into her house and stabbed her, after jumping over the perimeter fence of the Kiryat Arba settlement. Security guards rushed to the scene, and shot the assailant dead. An Israeli guard, 31, was also wounded in the attack, apparently by Tra'ayra who stabbed him before being shot.

"We have now confirmed that she is a U.S. citizen," State Department spokesman John Kirby said at a news briefing.

Hallel’s U.S. citizenship derives from her mother Rena Ariel, originally Rena Aranoff. Her extended family still has members living in both Israel and the United States, according to Rena's first cousin, Rachel Aranoff, a resident of Scarsdale, N.Y.

Rachel Aranoff said that when her relatives first called her from Jerusalem with the tragic news, “I was shocked and upset. Hallel's murder is a great loss to the entire Jewish people. We are all one family.”

At first, she said, she felt guilty when people began offering condolences after the murder because she hadn’t seen her Israeli family members in many years and hadn’t known Hallel well. But “hours and many tears later,” she realized her friends had been right to comfort her - the feeling of losing a relative to terrorism was new and devastating.

“Years ago, when a horror like this occurred, I was critical of parents who would live in an area where their children could be slaughtered by these barbarians. Unfortunately, over the last few years I have come to learn that Jews are slaughtered all over the world. Belgium, Paris, New York, Tel Aviv. The danger is in identifying as a Jew, it doesn't matter where you live.”

Rina’s brother, Zvi Aranoff, who lives in Brooklyn, posted emotionally in Hebrew on Facebook eulogizing his niece from afar, calling her “beautiful, charming in every way, social, clever, full of joy and life, humor, ambition and plans for the future.

"She was my first niece, the first grandchild in the family. There wasn’t anyone who didn’t love her, no one who wasn’t captured by her charm as soon as they met her. I loved her very very much and my heart is broken.

“She never hurt anyone, not a fly - her distaste for killing was part of her even from a young age when she chose to be a vegetarian. She loved to read, dancing modern dance in which she excelled, and wanted to be a doctor when she grew up. And now, this lovely girl who never did a bad deed, is no more. She was taken from us in such a cruel and shocking way, that I still can’t grasp the level of the horror. And every time that I think of her and how she was slaughtered, I cry and cry and cry.”

Aranoff called her murderer “barbaric and “scum” who demonstrated no value for life when he murdered his niece in her bed.

Hundreds attended Ariel's funeral in Kiryat Arba on Thursday evening. "How do you eulogize a 13-and a half-year-old girl? Your mom and dad are here. Tell me what should I say? Tell me the words you use to eulogize a flower,” her mother, Rena, said in eulogy.

Following the stabbing, Israel put the assailant's village, Bani Na'im near Hebron, under lockdown, and revoked permits for his relatives. Prime Minister Benjamin Netanyahu vowed to seek the demolition of his house soon.