Media outlets are reporting the tragic news, first broken by Radar, that Tim Russert, the host of NBC's Meet the Press and one of the most knowledgeable and respected political journalists around, has died of a heart attack. We'll bring you more details as they emerge.

Update: MSNBC is reporting that Russert collapsed while at work at NBC's Washington news bureau. Anchor Tom Brokaw, voice slightly cracking, invoked "personal privilege" to note that "this news division will never be the same." Andrea Mitchell, commenting on Russert's ability to carry the bureau through 9/11 and the years thereafter, added that "It is Tim who has taught all of us how to be better journalists... He is the preeminent journalist of our time in any measure."

Update 5:17 p.m.: The Washington Post reports that Russert collapsed while recording voice-overs for Meet the Press.