The chilling scene at the start of Donna Tartt's Pulitzer-winning novel, on which the movie is based, sees 13-year-old Theo lose his mother and barely escape himself through a crumbling pile of priceless art treasures at the Metropolitan Museum of Art.

The bombing is shown without sound and strictly from the foggy perspective of the child in flashback sequences, in part to avoid comparisons with incidents such as the 9/11 attacks in the same city, director John Crowley said at Toronto's film festival.

"With our perspective it felt wrong to reference real terrorist attacks," he said. "For you to have your head taken to that just didn't feel that appropriate."

Kidman, playing the mother of Theo's friend who is forced to take in the child following the bombing, said she had studied the effects of trauma for her UN ambassador work on war and crimes against women and children, as well as a number of film roles.

"So much of the time it is not screaming in the moment" but rather taking "a lifetime to process what has happened," she said.

"As an actor, a lot of times, when you're acting things that are very traumatic, your body doesn't know the difference," added Kidman, who recently played a murder detective in "Destroyer" and starred in Civil War drama "The Beguiled."

"Your brain says, 'Oh, this is real' ... and your body suddenly goes into that traumatic response."

Oakes Fegley, the child actor playing Theo, said shooting the scene on a soundstage was "extremely eerie."

"You can see it in the film, that he doesn't even react fully until he leaves the museum. And it all hits him at that one moment where he releases that scream," he said.

Crowley said that author Tartt had been provoked to write the scene after the Taliban's demolition of the two ancient, giant statues -- the Buddhas of Bamiyan -- in Afghanistan.

The director said he deliberately avoided gratuitous shots of the museum attack because he was deeply aware of the offense of "the erasure of something that had sat there for thousands of years, just gone ... and what that meant, for the time that we live in."

"My way into the offensiveness of the act in the gallery was to sort of keep it off stage, as it were," he added.

"Goldfinch" premieres Saturday night at the Toronto International Film Festival -- the largest in North America, which runs until September 15.