ISIS is claiming that a female American hostage was killed in a Jordanian airstrike carried out in retaliation for the execution by fire of pilot Moaz al-Kasasbeh; the woman's death is unconfirmed and many news outlets, including Slate for the time being, have chosen not to print her name because of her family's reported belief that she will be safer if it's not disclosed. From the New York Times:
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 woman, the only remaining American hostage held by the Islamic State, disappeared in August of last year after she drove into Aleppo with her Syrian boyfriend. Her colleagues received a proof-of-life video a few months later, showing her wearing a hijab and begging for her life.
The woman's capture was reported last August, when news reports identified her as a 26-year-old humanitarian worker. She is believed to be the terrorist group's last remaining United States hostage.