President Donald Trump and other top leaders of the United States were evacuated from an annual dinner of White House correspondents on Saturday night after an unspecified threat. There did not immediately appear to be any injuries.

The Secret Service and other authorities swarmed the banquet hall as guests ducked under tables by the hundreds. “Out of the way, sir!” someone yelled. Others yelled to duck.

Trump’s attendance at the gathering in Washington for his first time as president is putting...