Dan Farrell, whose photograph of a young John F. Kennedy Jr. saluting during the 1963 funeral ceremonies for his slain father became one of the most memorable images surrounding the Kennedy assassination, died Monday at a hospital in Rockville Centre, New York. He was 84.

The cause was pneumonia, said a son, Daniel Farrell.

On Nov. 25, 1963, Farrell was on assignment in Washington for his newspaper, the New York Daily News, covering the funeral of President John F. Kennedy, who had been killed three days earlier in Dallas.

After beginning his day at the U.S. Capitol, Farrell moved to a spot across from St. Matthew’s Cathedral in downtown Washington. He stood on a crowded flatbed truck alongside scores of other photographers, about 150 feet from the cathedral’s front door.

Fifty years later, Farrell recalled the scene in an interview with the Daily News. “It was the saddest thing I’ve ever seen in my whole life,” he said.

When the mourners emerged from the cathedral, Farrell trained his Hasselblad camera on the Kennedy family. As the president’s casket was placed on a horse-drawn caisson, his widow, Jacqueline Kennedy, leaned down and said something to her son. It happened to be his third birthday.

Farrell was watching through a telephoto lens.

“She said, ‘John, salute,’ ” he recalled in 1999. “He didn’t respond at first. I took a deep breath. She said, ‘John-John, salute.’ ”

The young boy, wearing a light blue jacket and short pants, stepped forward and raised his right hand to his brow. Farrell snapped just a single frame.

Other members of the president’s family, including his widow and brothers, are visible in Farrell’s original picture, but it is dominated by the quiet gesture of its smallest figure.

The moment was captured on newsreel film and by at least one other photographer, Stan Stearns of United Press International.

Farrell’s photograph, sometimes cropped to show only John Kennedy Jr., was sent out on the Associated Press wire service and became an enduring symbol of one of the most solemn days in the country’s history.

“One shot. One frame,” Farrell said in 2003. “And it was all over.”

Daniel Boyle Farrell was born Oct. 31, 1930, in Hazleton, Pennsylvania, and grew up in Brooklyn. He served in the Navy before joining the Daily News as a copy boy about 1950.

Early in his career, he rode a motorcycle all over New York City, picking up film and delivering it to the newspaper office. He soon became a photographer and, in a career of more than 45 years, became one of the tabloid paper’s most admired staffers.

“You’re not a staff photographer here unless you’ve worked with Dan ‘the Man’ Farrell,” Daily News photographer Mike Lipack told the St. Louis Post-Dispatch in 2001. “He’s got more stories than I’ve got memories.”

Farrell covered the Beatles and Rolling Stones, all the major New York sports teams, the 1971 heavyweight championship fight between Muhammad Ali and Joe Frazier and even a meeting of Marxist revolutionary Che Guevara and poet Allen Ginsberg.

One time, on assignment to photograph Marilyn Monroe riding atop an elephant at Madison Square Garden, Farrell found her trembling in fear.

“I knocked on a door and found her in this room by herself,” he said in 2001. “I said, ‘You don’t have to do this.’ She said, ‘Yes, I have to.’ ”

Farrell officially retired in 1996, but he continued to take pictures for the Daily News for another decade. He never went anywhere without a camera around his neck.

His wife of 55 years, Mary Martin Farrell, died in 2012.

Survivors include five children, Daniel M. Farrell of Bridgewater, New Jersey, Lynn Farrell of Freeport, New York, Kathy Natoli, Christine McCormick and Mary Ligarzewski, all of Oceanside, New York; three brothers; a sister; 19 grandchildren; and eight great-grandchildren.

Farrell was nominated for a Pulitzer Prize for his photograph of John F. Kennedy Jr., but he lost to the Dallas Times-Herald’s Robert H. Jackson, who captured the moment when suspected assassin Lee Harvey Oswald was shot by Jack Ruby.

But after more than half a century, few images capture the tragedy of the assassination more vividly than Farrell’s photograph of a young son, at his mother’s urging, offering a final salute to his departed father.

“I can still see her face,” Farrell said in 1999, “see her lips moving, ‘John-John, salute.’ “