After the gunshots, JD Vance was first to be pulled off stage, then Trump and the first lady. Someone started a ‘U.S.A.’ chant but was shushed

The White House Correspondents’ Association dinner is one of Washington’s enduring, if somewhat awkward, rituals.

There is inherent tension in the room, with journalists dressed in finery sharing drinks and food with many of the subjects they cover. That friction was starkly evident this year given President Donald Trump’s often contentious relationship with the media.

That ritual was wildly upended Saturday night when a gunman charged the premises, trying to penetrate the hotel ballroom where Trump and Cabinet secretaries were assembled. They were spirited out unharmed and the crowd of 2,300 hunkered down in gasps, confusion, broken plates and spilled wine.

Wait, was that the sound of a gunshot? Trump wondered. Or did some waiter just drop a tray? “I was hoping it was a tray,” Trump said. “But it wasn’t.”

Oz Pearlman, the mentalist enlisted as the evening’s entertainer, was performing a magic trick for Trump on stage as shots rang out outside the ballroom, he told The Associated Press, which had two dozen journalists there.

Trump had boycotted previous dinners as president. It was apparent, going into the dinner, that he had things he wanted to say about the...