Journalists in the nation’s capital are accustomed to chasing stories. But on Saturday night, the story came to them — hundreds of them, gathered as President Donald Trump prepared to speak, thrust suddenly into chaos when a gunman tried to storm the annual White House Correspondents' Association dinner. In the aftermath, safety and coverage blended as some of the nation's most powerful reporters and editors tried to figure out what was unfolding in front of them. Or in many cases, above them. Many of the journalists, clad in tuxedos and gowns, had ducked for cover in fear, bewilderment or just plain instinct. “We were under the table before we knew what was happening,” The Atlantic magazine journalists Missy Ryan, Matt Viser and Michael Scherer wrote of their experience. When they emerged, mobile phones were the tools of their trade — to shoot pictures or video, record interviews or keep a phone line open to describe the scene to colleagues working the story off-site.…