ISIS has claimed that a 26-year-old female American hostage was killed in an airstrike in Syria, according to NBC News partners Flashpoint Intelligence.
Defense officials told NBC News that U.S. military and military intelligence have no information to confirm ISIS' claim, and the State Department said it could not confirm reports of the death "in any way."
"We are obviously deeply concerned by these reports. We have not at this time seen any evidence that corroborates ISIL's claim," said Bernadette Meehan, spokeswoman for the National Security Council said.
Kayla Mueller, originally from Arizona, was taken hostage by ISIS in Syria on Aug. 4, 2013, while leaving a Spanish Doctors Without Borders hospital. Previously, Mueller's family had requested that her name not be made public.
According to a statement released by a representative of her family on Friday urging caution in reporting on Mueller's situation, "the common thread of Kayla's life has been her quiet leadership and strong desire to serve others."
In a report distributed on Twitter, ISIS stated that the hostage was buried in the rubble of a building hit by Jordanian aircraft. Jordanian warplanes have pounded ISIS targets in Syria since the militants released a video that appeared to show a captured Jordanian fighter pilot being burned alive in a cage.
State Department spokeswoman Marie Harf said Friday: "I cannot confirm those reports in any way. Obviously people are looking into them, but cannot confirm them." When asked if she knew if the hostage was alive, Harf said: "We're just not going to get into specifics about Americans being held overseas."
One senior defense official told NBC News "the entire intel community" in the U.S. government "lit up immediately at the ISIS claim and is attempting to gather the facts." The official also said that if, in fact, the American woman has been killed it could be impossible to verify if was the result of an airstrike.
Recently, President Barack Obama has said the U.S. is deploying "all assets" to save the hostage.
Jim Miklaszewski contributed reporting to this article. This is a developing news story. Please check back for updates.