All the major networks broke into regular programming as this morning’s horrific elementary school shooting in Connecticut unfolded. A visibly shaken President Barack Obama held back tears as he spoke of the tragedy. News anchors and reporters also showed their emotions while reporting details. (CNN’s Ashleigh Banfield from the scene spoke movingly about how her two small children attend school in Connecticut just 30 minutes away.) Cable networks devoted blanket coverage and networks adjusted schedules. All three evening anchors – Brian Williams, Diane Sawyer and Scott Pelley – will be anchoring from Newtown, Connecticut, tonight. The CBS Evening News will expand to one-hour, and CBS will air a one-hour special report at 10 PM ET. ABC World News will also be one-hour with Diane Sawyer beginning at 6:30 PM ET. ABC will pre-empt Barbara Walters‘ interview with President Obama and First Lady Michelle Obama for Sawyer and Chris Cuomo to anchor a special edition of 20/20 (10-11 PM ET). There’s also a special edition of Nightline with Cynthia McFadden. Brian Williams will anchor a special one-hour edition of NBC Nightly News from Newtown at 6:30 PM ET. Dateline will preempt its holiday special while Williams and Lester Holt anchor a special one-hour devoted to the shooting at 10 PM ET. On Saturday, Matt Lauer and Savannah Guthrie will co-anchor a special edition of Today live from Newtown, along with Holt and Erica Hill. Ann Curry and Willie Geist will report.