ET has learned that "NBC Nightly News" anchor BRIAN WILLIAMS had to forfeit hosting the 67th Annual George Foster Peabody Awards ceremony today in New York City, due to the loss of his esteemed colleague TIM RUSSERT, who died on Friday of a heart attack.

Returning from assignment in Afghanistan, Williams explained the circumstances and reflected on Russert with a statement, saying, "I hope you can all understand the degree to which our NBC News family is hurting right now. This morning represents my first opportunity to see my friends and co-workers and speak with our staff, as I just returned from Afghanistan a few hours ago.

"Of course, what makes this so sad has a lot to do with what the Peabodys represent: we have lost a great practitioner of our craft. We've lost a great friend, a great man, and some of us have lost a partner. My congratulations to this year's recipients, my thanks to LESLEY [STAHL] for being there -- and may god bless Tim Russert."

CBS' Stahl stepped in for Williams as a last-minute replacement host. According to The Huffington Post, she remarked in her opening speech, "He was the Washington Bureau Chief at NBC when I was moderating 'Face the Nation,' and if I did a particularly good interview, the first person who would call me was Tim Russert. And it's small and it's insignificant to all of you, but it's just one more little act of kindness and that was who he was."