Homeland Security Secretary Gen. John Kelly said it was "outrageous" that unnamed U.S. officials leaked intelligence information about the Manchester, U.K. terror attack.

On "Fox News Sunday," Chris Wallace recalled how shared U.K.-U.S. intelligence about the attacker, Salman Abedi, and the attack itself leaked to the media.

"It's outrageous," Kelly said. 

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Kelly added that he called his British counterpart, Home Secretary Amber Rudd, to offer assistance and express condolences for the attack.

When the intelligence information was leaked, British Prime Minister Theresa May blasted the revelations in a televised statement.

"I don't know why people do it," Kelly said of the leaks. "It jeopardizes not only the investigation, but people's lives."

After the leak, Secretary of State Rex Tillerson apologized to May and MI5.

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