The photograph of a bloodied Donald Trump with his fist in the air and an American flag looming in the background is quickly emerging as the pivotal image of Saturday's shooting, and it wouldn't exist without a journalist who acted quickly and on a hunch.

Video of the assassination attempt at a Pennsylvania rally featuring the ex-U.S. president filled television screens before it was even clear what had happened. Yet the work of The Associated Press's Evan Vucci, Getty's Anna Moneymaker and Doug Mills of The New York Times — whose picture caught apparent evidence of a bullet whizzing past Trump's head — proved the enduring potency of still photography.

Vucci's image, one of many he took on Saturday, could also have political implications, as images often do in the days and years after seismic events.

"Without question, Evan's photo will become the definitive photo from the [assassination] attempt," said Patrick Witty, a former photo editor at Time, The New York Times and National Geographic. "It captures a range of complex details and emotions in one still image — the defiantly raised fist, the blood, the agents clamouring to push Trump off stage and, most importantly, the flag. That's what elevates the photo."

Vucci was one of four news photographers stationed between the stage and audience on Saturday.

When he heard popping sounds, Vucci, who has covered combat situations in Iraq and Afghanistan, said he knew instantly it was gunfire. He rushed to the stage at Trump's right, but his view of the former president was quickly blocked by Secret Service agents. He sensed that the agents would try to hustle Trump offstage and into a vehicle from the other side, so he darted over there.

From that position, Vucci said, "everything kind of opened up for me."

Trump's attempts to rise to his feet and pump his fist gave Vucci a clear view of the ex-president. He said the blue sky and flag in the background were an important part of the composition.

"I think that kind of told the story of where we are right now," he said.

"The way I look at it is: I was present, and I did my job," said Vucci.

Witty, like some others, compared it to Joe Rosenthal's AP photo of U.S. Marines raising the American flag on Iwo Jima in the Second World War — an image so memorable to so many that it inspired a memorial.

"I think it will last and come to symbolize the time that we're in," said Ron Burnett, former president of the Emily Carr University of Art and Design and an expert on images.

Photo taken by Doug Mills for the New York Times:

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It's not hard to imagine the flag-draped image being seen in Trump campaign advertisements or paraphernalia, much like his mug shot from his Georgia arrest quickly did. At least one website was already selling T-shirts with the photo on them.

"I can see it being used in a whole variety of ways as part of the entourage of images that he surrounds himself with," said Burnett.

There was other impressive work by photographers at the scene. Getty's Moneymaker, for example, caught an extraordinarily intimate image of Trump on the floor of the stage, taken peephole-style through the legs of a Secret Service agent shielding him.

Mills's photograph for The Times is one of a series that shows Trump reaching for his ear after it had been hit. In one of them, barely visible unless the photo is blown up, there's a streak behind Trump's head that likely illustrates the displacement of air from a fast-moving projectile, according to a retired FBI special agent quoted in the newspaper. The Times did not discuss the issue on Sunday.

The agent, Michael Harrigan, told the newspaper: "Given the circumstances, if that's not showing the bullet's path through the air, I don't know what else it would be."