The Islamic State claims that U.S. hostage Kayla Mueller was killed Friday in a Jordanian air strike on Raqqa, according to The New York Times.

Mueller, a 26-year-old humanitarian worker from Prescott, Arizona, had been captured in August, 2013 after leaving an Aleppo hospital run by Doctors Without Borders. She is the only known remaining American hostage held by the organization.

“The failed Jordanian aircraft killed an American female hostage,” said a message published by the SITE intelligence group. “No [fighter] was injured in the bombardment, and all praise is due to Allah.”

The claim has not been verified, as the group did not publish photos of the North Arizona University graduate. It is highly likely that the declaration is aimed at provoking Jordan and world leaders in retribution for the recent air raids.

“An old and sick trick used by terrorists and despots for decades: claiming that hostages human shields held captive are killed by air raids,” wrote Nassar Judeh, Jordan’s foreign minister, on his Twitter account.

Bernadette Meehan, spokesperson for the White House National Security Council, affirmed that the United States was “deeply concerned” about the report, but that there was not “any evidence that corroborates” the ISIS claim.

The Islamic State has recently beheaded three other Americans, two Japanese, and two British hostages, making the events highly emotional and sensational for both the media and the countries involved. The current claim about Kayla Mueller has come a few days after a recent video which showed Mouath al-Kasaesbeha, a Jordanian pilot, being burned alive.

King Abdullah, who had been in Washington discussing the problem, had immediately ordered an increase in Jordan’s role in the U.S.-led coalition against the group.

“We are waging this war to protect our faith, our values and human principles, and our war for their sake will be relentless and will hit them in their own ground,” stated Abdullah.

Kayla Mueller’s family had asked that she remain unidentified while in captivity, but her identification and origin by the Islamic State’s statement in the Jordan air strike on Friday prompted them to confirm the information.