It appears we just got Banksy-ed,” said Alex Branczik, Sotheby’s head of contemporary art, Europe, to The Art Newspaper shortly after a bizarre incident at the famed auction house. On October 5, a painting by the anonymous street artist and activist known as Banksy went under the hammer for £860,000 or $1.042 million which set a new record for the artist. It was the final lot for that evening, and no sooner had the hammer come down, the canvas began to slide down and through its faux-gilt frame. As it slid out, the canvas was neatly shredded into strips. When about half the painting was shredded, it stopped, leaving everyone in the room bemused.

The artwork, known as ‘Balloon Girl’ or ‘Girl with a Balloon’ first appeared as a graffiti mural on the wall of a printing shop in Shoreditch, London, in 2002. It depicts the silhouette of a young girl stencilled with black paint, releasing a red heart-shaped balloon into the wind. The original mural was controversially removed by the events company, Sincura Group, and sold for £500,000 on September 19, 2015. The Balloon Girl auctioned by Sotheby’s on October 5, was an original remake by the artist on canvas which was acquired by the auction house in 2006.

Ever since the original mural first appeared, it has courted controversy and polarised opinions. Banksy has reproduced several versions of the mural on various occasions. On the third anniversary of the Syrian conflict in 2014, Bansky altered the painting to replace the girl with a Syrian refugee and projected it onto the Eiffel Tower and Nelson’s Column. A few weeks later Justin Bieber got a tattoo of the painting done on his arm, which he posted on Twitter, only to delete it shortly afterwards. Banksy reposted the photo on Facebook with the comment “controversial”.

Last year, the BBC reported that Balloon Girl was “Britain’s favourite artwork” based on the findings of a survey conducted by Samsung. The survey asked 2,000 UK residents to select their favourite artwork from a short-list of 20 works drawn up by art editors and writers. Balloon Girl was chosen over the likes of The Hay Wain by John Constable, The Singing Butler by Jack Vettriano, and JMW Turner’s The Fighting Temeraire.

Banksy’s satirical street art, sometimes combined with epigrams, uses a distinctive stencilling technique. His works have appeared on the walls and public spaces of cities throughout the world. He is credited for being one of the pioneers of using street-art to fight the occupation in Gaza and West Bank. His works have touched upon issues such as the Syrian conflict, the refugee crisis in Europe, child-labour, Brexit and even the British general election.

He is arguably the greatest British street artist, and tonight we saw a little piece of Banksy genius.” – Alex Branczik, Sotheby’s head of contemporary art, Europe.

He also confirmed that he or Sotheby’s were “not in on the ruse” to shred artwork. The artist, however, went out of his way to confirm that it was his plan all along. He posted a video on his Instagram account which shows him placing the blade and other components of the shredder within the frame with the caption: “A few years ago I secretly built a shredder into a painting… in case it was ever put up for auction.” The video then cuts to the footage shot inside the auction room where the shredder is shown doing what it was meant to do.

The “ruse” left the art world figuratively scratching their heads which included the normally self-assured individuals at Sotheby’s. “We are busy figuring out what this means in an auction context,” said Branczik. “The shredding is now part of the integral artwork. We have not experienced a situation where a painting has spontaneously shredded, upon achieving a record for the artist.

There are also technical and legal issues to consider. The sale had concluded by the time the shredding began. “The successful bidder was a private collector, bidding through a Sotheby’s staff member on the phone. We are in discussions about the next steps,” Sotheby’s said in a statement.

Normally, if an artwork is damaged after it is sold, and before it leaves the auction house, the sale is cancelled. However, this is by no means a normal sale. According to a growing chorus of experts, the value of the art may now increase given the widespread publicity the painting has received, and more so because of its uniqueness as a document of the guerrilla tactic.