Transcript for Iconic artwork 'shreds itself' after selling for $1.4 million

And we E are back now with that stunning $1.4 million prank the artist banksy shocking guests at a London auction house, one of his signature works shredded just after it was sold. ABC's T.J. Holmes is here with how he did it and why the painting now could be worth even more, T.J.? Yes, banksy is a world famous yet anonymous street artist. He has railed for years against people trying to make money off his art. Art and the excesses of the art world. But this weekend he went mission impossible on the art world. This piece of art will self-detruck in five seconds if you dare try to sell it at auction. That's a $1.4 million piece of art self-destructing for all the world to see. Girl with balloon from banksy on sale at sotheby's in London this weekend. It had just sold for that 1.4 mill. And as soon as it did, an alarm sounds. The canvas starts sliding down and shreds in front of bewildered fans and collectors alike. Soon after banksy posted this photo on Instagram writing, going, going, gone. Then this video showing how he secretly built a shredder inside the painting's frame years ago in case it was ever put up for auction. As dramatic as this was, it's not necessarily uncharacteristic for banksy. The elusive artist who never revealed his true identity to the public famous for creating anti-establishment and provocative works he also loves pranks like sneaking this fake cave painting into the British museum where it stayed for several days undetected. But his latest hoax pulled off so brilliantly and flawlessly, some wonder if the auction house was in on it saying the unusually thick size of the frame should have raised eyebrows. Also noting that paintings this size are usually placed on easels and one more thing, the timing was a bit suspicious as it was the last painting for auction at the end of the night. And it was an anonymous bidder so if you're on the phone and spent 1.4 million and what you just invested in goes into shreds, you might be up set or would you because they're saying now it's possibly going to be worth a whole lot more because it's now a part of art history. Oh, my goodness. Okay. I don't get art either. There's so many questions here but, one, banksy, was he in the auction room because someone had to set off the shredder, right? Speculation is he could have sent somebody in there, sure, but now there's someone in the room people point to and say that might be the guy right there. He had on glasses, looked a little suspicious -- somebody had to be there because this painting was given personally by banksy to someone in 2006. That's a heck of an energizer battery. Someone had to have access to it recently possibly to switch out -- the mystery -- we won't figure it out. I'm the best journalist I can be. Do you still hang it on the wall all shredded up. Yes, you could put it back together. They got people who can piece these together but you want to show -- I own art history now from banksy. Okay. Or a big old prank.

This transcript has been automatically generated and may not be 100% accurate.