A U.S. drone strike early Friday is believed to have killed the notorious “Jihadi John,” the masked ISIS militant widely known from the beheading videos of several Western hostages. Prime Minister David Cameron said the intelligence services couldn’t be certain that the individual believed to be British-born Mohammed Emwazi was dead, but thanked the U.S. for launching the airstrike against the terrorist. Citing a top U.S. official, a BBC source said the Pentagon had a “high degree of certainty” that a targeted strike hit Emwazi, along with another person in a car in the ISIS stronghold of Raqqa, Syria. Officially, the Pentagon said it was still “assessing the results of tonight’s operation.” An official told ABC News that Emwazi was “eviscerated” in a “clean hit” with no collateral damage. The militant first appeared in a video from the self-proclaimed Islamic State in August 2014, when American journalist James Foley was beheaded. He also is believed to have participated in the executions of American journalist Steven Sotloff, American worker Abdul-Rahman Kassig, British aid workers David Haines and Alan Henning as well as Japanese journalist Kenji Goto.