From the Boston Globe's Tuesday editorial, following the Boston Marathon bombings:
Many news organizations already had reporters, photographers, and videographers in place at the Marathon’s finish line, allowing initial news reports from the scene of the explosions to emerge quickly. Social media feeds filled rapidly with eyewitness accounts, public safety announcements, and up-to-the-minute reporting.
But, crucially, there was also a sense of measured restraint. Four months ago, in the immediate aftermath of the shootings at Newtown, Conn., reports misidentifying the perpetrator were widely retweeted. That tragedy left its mark on social media. Journalists, especially, were clearly warier Monday about letting misinformation spread. Many tweets, for instance, were careful to cite specific sources or to assure readers of multiple confirmations. It seemed that, for one day, being first had taken a backseat to being right.