Maria Puente, Andrea Mandell, and Bryan Alexander

USA TODAY

Oscar got it wrong, wrong, soooo wrong. The presenters announced the wrong Best Picture; Moonlight was the winner, not La La Land.

It was the biggest, most embarrassing, most awkward mistake in the history of the Academy Awards, played out before an audience of millions watching on TV and a theater full of stars standing, stunned, mouths agape, as a chaotic scene unfolded on stage at the Dolby Theater after midnight ET.

How could it happen?

USA TODAY had reporters stationed in all parts of the theater. Here's what we know:

On stage:

Warren Beatty and Faye Dunaway were presenting but looked lost. When he opened the envelope, he paused for a long few seconds. He looked at Dunaway, puzzled. She took the envelope, read it, paused, and said, "La La Land."

Up came the cast and crew of the much-heralded film. They started making their acceptance speeches.

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Backstage:

As the La La Land filmmakers take the stage to accept best picture, the accountant from PriceWaterhouseCoopers jumped up and said, "He (Beatty) took the wrong envelope!" and goes running onstage. Craziness breaks out. No one knows how Beatty got the best actress envelope instead of the best picture envelope.

"Oh, my God. Moonlight won, Moonlight won," a stagehand says, her hands on her head.

Around 3 a.m. ET, PriceWaterhouseCoopers would issue a statement explaining, "The presenters had mistakenly been given the wrong category envelope and when discovered, was immediately corrected. We are currently investigating how this could have happened, and deeply regret that this occurred."

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On stage:

After receiving a rousing hurrah from the crowd, Jordan Horowitz, the producer of La La Land, took the mic, waving one finger in the air and saying, "Sorry, guys, hold on. There's a mistake. Moonlight, you guys won best picture. This is not a joke."

He held up the card and the camera came in close: It said Moonlight and its producers' name.

After confirming Moonlight was the rightful best-picture winner, the Oscars crowd erupted into cheers. Beatty took the mic again to explain the flub.

"I wanted to tell you what happened. I opened the envelope, and it said, “Emma Stone, La La Land,” that’s why I took such a long look at Faye, and at you, I wasn’t trying to be funny."

Host Jimmy Kimmel was beside himself but tried to joke. "Warren, what did you do?!" He said what happened was "very unfortunate. Personally, I blame Steve Harvey for this." (Harvey's notorious for naming the wrong Miss Universe winner in 2015.)

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On the mezzanine

Audible gasps escaped from the mezzanine, with Oscars guests turning to each other and whispering, "What?" Onlookers looked deflated; they were mostly La La Land die-hards. Only a handful stood and clapped when Moonlight was announced as the rightful winner. The mood was in stark contrast to what was going on in the lower level where the applause was strong.

Backstage:

The Moonlight filmmakers pour backstage, with director Barry Jenkins holding the Oscar and muttering, "Oh, my God, oh, my God." Everyone looks befuddled.

“I’m sure everybody saw my face. I was speechless," Jenkins told reporters in the press room later. "That was awkward. It made a very special feeling even more special, but not in the way I expected....Please write this down. The folks from La La Land have been so gracious. I can’t imagine being in their position."

"I feel so weird," best supporting actor winner Mahershala Ali says. "Now, that was awkward." He runs into La La Land star Ryan Gosling, who is smiling in spite of it all, and they hug.

“When (La La Land)'s name was read, I wasn’t surprised," he added. "I’m really happy for them, a group of some extraordinary people in front of the camera and behind the camera. Then, when I did see the security people coming out on stage and their moment was being disrupted in some way, I got really worried."

He was really thrown when it turned out Moonlight was the winner. "I didn’t want to go up there and take it from somebody. It’s very hard to feel joy in a moment like that.… But I feel very fortunate for all of us to walk away with Best Picture. It's pretty remarkable."

La La Land director Damien Chazelle keeps his game face. "That was weird," he says.

Security is looking for Beatty, who had both envelopes. There's much confusion, because Oscar staffers carefully check presenters before they walk out, to make sure they have the right envelope in hand.

"What just happened?” Kimmel says, walking back to his dressing room in shock.

"I think for the rest of my life, I'm going to be asked about this," Kimmel says. "And I'm trying to remember the details correctly. My guess is it's going to be it's operator error. I don't know anything."

Later, he adds, "I really should go speak to Warren."

Adam Carolla, representing the show writers, gives a speech backstage praising Kimmel's show. There are shouts of "Best show ever! Best show ever!"

Meanwhile, in the press room:

Shock hit the press room backstage like a tidal wave, as roughly 100 journalists stared at the screen, their mouths open. The most common refrain was a stunned “What?!”, followed by choice expletives (“holy s---“) and, “Am I really seeing this?” as reporters tried to discern if they were watching a planned bit or the biggest Oscar flub ever.

“I was actually holding my best actress card the whole time," winner Emma Stone of La La Land, told reporters. "So I’m not sure what happened, but I wanted to talk to you guys first."

But she was authentically happy for the actual winner. "I (bleeping) love Moonlight. I love Moonlight so much. I’m so excited for Moonlight.… We are so excited for Moonlight. I think it’s one of the best films of all time.”

But was it "the craziest Oscar moment of all time?” Stone asked reporters. Uh, yes. “Cool! We made history tonight.”

Ten minutes after the broadcast ended, disbelief continued, as journalists, who had previously thought their headlines were in the bag, scrambled to rewrite. For better or worse, the consensus can be summed up by one reporter sitting across from USA TODAY:

“Most epic ending to the Oscars ever.”

Contributing: Jaleesa Jones