WASHINGTON (CNN) -- "Jihadi John," the jeering, sadistic masked mouthpiece of ISIS, may have been killed in a U.S. airstrike in Raqqa, Syria.
While the Pentagon, in announcing the strike Thursday night, wouldn't definitely say Mohammed Emwazi was dead, U.S. officials said authorities are confident he was.
This was a mission of "persistent surveillance," a senior U.S. official said, adding that authorities knew it was Emwazi when they took the shot.
Another U.S. official told CNN that Emwazi was in a vehicle at the time of the strike, which was launched from a drone.
A most wanted man
Emwazi, a British citizen, was a most wanted man.
As the masked face of ISIS, he appeared in a series of brutal execution videos, dressed head-to-toe in black and holding a knife.
He took part in the murders of U.S. journalists Steven Sotloff and James Foley, U.S. aid worker Abdul-Rahman Kassig, British aid workers David Haines and Alan Henning, Japanese journalist Kenji Goto, and a number of other hostages, the Pentagon said.
The Ramadhan Foundation, a Muslim organization in the UK, said Emwazi was the manifestation of the evil.
"The killing of Mohammed Emwaz in Syria is a significant moment in the fight to get justice for David Haines, Alan Henning and all the victims of this evil man," said Mohammed Shafiq, the group's executive director.
The strike appeared to have taken place Friday in Syria (Thursday night in the U.S.).
Syrian activists in Raqqa reported that four ISIS foreign fighters, including a leader with British nationality, were killed by coalition airstrike, the Syrian Observatory for Human Rights said.
British Prime Minister David Cameron was aware of the airstrike, and notified families whose kin was executed by Emwazi.
"Britain has been working hand in glove with America over the 'Jihadi John' drone strike, to defeat (ISIS), and to hunt down those murdering hostages," Cameron's office said. "The Prime Minister has said before that tracking down these brutal murderers was a top priority."
A frequent video presence
Emwazi, who speaks English and is believed to be born in Kuwait, was frequently seen in hooded hostage videos carrying out violent beheadings.
For periods at a time this year, Emwazi was not seen in hostage videos, though U.S. officials told CNN in July that they had learned that he was alive and hiding near Raqqa.
Analysts describe him as grotesque and fond of sadistic torture techniques, with one former hostage recounting last month how his captor made him dance the tango with him.
CNN's Theodore Schleifer contributed to this report.