Quoting the New York Times,

Officials noted that the suspect never made it into the hotel ballroom, where President Trump and hundreds of journalists were gathered for the White House correspondents’ dinner.

Not so fast. Quoting (NY Post) Witness describes the moment gunman Cole Allen was taken down after White House Correspondents’ Dinner shooting , which quotes Erin Thielman,

“As soon as my son answered the phone, I said, ‘Hey, bud,’ and I heard three loud bangs,” she recalled to The Post. “It was gunshots. I looked to my left. I saw Secret Service with their pistols drawn, probably just had shot. Like right in front of me, he was a foot away,” she said of the suspect, Cole Allen, 31, after Secret Service took him down. “The would-be assassin fell face-first, and his hands were out in front of him.

Why did Allen fall to the ground?

• It has been established that he was not shot.
• He could have heard a command, though Thielman doesn’t mention hearing one.
• He could have been tackled, which Thielman has not mentioned.
• He could have imagined he had been shot, which often causes an instinctive fall.
• He could have lost his balance, or tripped.

Had Allen not fallen, had he entered the stairs proper, he would have had to navigate a landing, a 180 degree turn, the bottom landing, and a 90 degree turn to face the ballroom door. Had he not tripped, with sufficient speed, the first landing would have provided cover from Secret Service agents attempting to down him with gunfire. And fast he was, considering how far ahead he was before he  fell. Once in the ballroom, the risk of civilian casualties becomes huge.

Why did this happen? This was a continuation of recent complacency. The Secret Service doubtless anticipated that a heavily armed assassin might try to storm the checkpoint. They did not anticipate that an individual would prioritize speed. There was nothing to slow Cole down; the reaction time at the checkpoint was slowed by the balancing requirement of public safety with the use of deadly force.

The fix is simple. The checkpoint should have had a portable turnstile, or a back-and-forth path of the kind used to organize long lines, which would have slowed Cole down to enable proper scrutiny. It is so simple, it’s a kind of test.  Will the press will properly engage the  the Secret Service about how sharp they are?

After all, it was their dinner.