Thirty years ago today, President Ronald Reagan was shot by would-be assassin John Hinckley Jr. outside the Washington Hilton.

One of the Metropolitan Police officers assigned to the presidential detail that day — and one of the lawmen closest to Hinckley as he started shooting — was Leon J. Swain Jr., now chair of the D.C. Taxicab Commission.

Swain, 58, has gone on to some notoriety in recent years for his crucial role in exposing a taxi industry bribery conspiracy. But on March 30, 1981, Swain was a young cop who found himself in the middle of history as it was made.

In the ABC News video linked above, at about 0:55, the camera pans across Swain’s face just as the shooting begins. After that moment, Swain can be seen in photos as one of several officers and bystanders pressing Hinckley against the wall of the Hilton. A fellow D.C. cop, Thomas Delahanty, was one of the four men struck by Hinckley’s bullets. (For the definitive retelling of that day, you must, must! read “Rawhide Down,” the new book by my Post colleague Del Quentin Wilber.)

Swain, reached today at the Taxicab Commission, recalled that Monday afternoon three decades ago: “It doesn’t seem like it’s been 30 years. ... The thing that got me was how quickly it happened.”

He said he’s kept in sporadic touch with some of the other law officers on the scene that day, including Secret Service agent Danny Spriggs, who can be seen after the shooting next to Hinckley at the Hilton wall, holding a revolver. “It takes a lot of stones to go rushing when people start shooting,” Swain said. “I’m glad I know people like that.”

Swain was by matter of chance the man that drove Hinckley downtown to the D.C. central cell block. On NBC News video (about 6:55), you can see Swain among the law officers who try to shove Hinckley into one squad car, only to find its door locked. He is taken to another car, which Swain got into and took the wheel.

“He just had this plain look on his face,” Swain recalled. “There was no look of concern whatsoever. ... I looked up in the rearview mirror; I’m looking at his face, and I said to myself, ‘Damn, this guy just shot the president of the United States.’”

Swain said he’s visited the Hilton a couple of times since the shooting, but not to reminisce. “I haven’t felt the need to go make a midnight journey back to the wall,” he said. “The whole facade has changed a little bit.”