UPDATED, 9:40 AM: ABC News and NBC News said they will expand their evening newscasts to an hour tonight to cover the aftermath of the Oklahoma tornado that so far has killed 24 including many children stuck in their schools. On CBS, the CBS Evening News With Scott Pelley is expanding to 90 minutes from 6:30-8 PM. ABC also is airing a special edition of Nightline dedicated to tornado coverage, and ABC News’ David Muir, Ginger Zee, and Mike Boettcher will report in from Oklahoma this afternoon on Katie.

PREVIOUS, MONDAY PM: The network and its sister outlets MSNBC and the Weather Channel will focus Tuesday on coverage of today’s massive twister that cut a huge swath of destruction near Oklahoma City. Along with live coverage from devastated Moore, OK, on NBC’s Today and MSNBC’s morning programs, the broadcast network will air a one-hour special hosted by Brian Williams live from the scene at 8 PM ET (delayed in other time zones). That will pre-empt a recap show of The Voice featuring the top 10 performances; a new live episode of the singing competition will air as scheduled in the 9 PM hour. Meanwhile, the Williams-anchored NBC Nightly News is slated to run in its regular half-hour starting at 6:30 PM and is not expected to be expanded. Today’s Matt Lauer, Savannah Guthrie, Al Roker, Natalie Morales and Willie Geist also will report from Moore, as will Lester Holt, Ann Curry, Kate Snow and others. MSNBC anchors reporting live from suburban OKC will include Joe Scarborough, Mika Brzezinski, Chris Jansing and Thomas Roberts.