An Islamic State message published by the SITE Intelligence Group, which tracks jihadist activity, said the American woman was killed when the building where she was being held in the Raqqa area collapsed in an airstrike.

“The failed Jordanian aircraft killed an American female hostage,” said the message. “No mujahid was injured in the bombardment, and all praise is due to Allah.” Mujahid means fighter.

The group said the woman was killed by “fire of the shells dropped on the site.”

There was no immediate way to verify the claim by the Islamic State, also known as ISIS or ISIL. But it identified the hostage by name, Kayla Jean Mueller, for the first time, and gave her Arizona address, apparently to add credibility to its message.