Just one window-pane had been removed from Paris's Museum of Modern Art, neatly carved out. But that is all it took for a masked intruder to commit one of the most audacious art thefts in years, making off with €100m (£86m) of art, including a Picasso and a Matisse.
Yesterday, paper signs on the doors of the museum by the Seine, next to the Palais de Tokyo and across the riverbank from the Eiffel Tower, said it was closed "due to technical reasons". Red-and-white tape warned people not to approach the scene, while police and security staff blocked the most persistent from getting too close.
While people from the art world expressed their disbelief that a robbery of this size could have been the work of one thief alone, police were working behind the cordoned-off balcony where the robber – or robbers – had committed their crime, to find out just how the theft had taken place.
The paintings, including Picasso's 1912 oil painting, Le pigeon aux petits pois (Dove with Green Peas), estimated to be worth €23m, and Henri Matisse's Pastorale (Pastoral, 1906), valued at €15m, appeared to have been carefully removed from disassembled frames, rather than sliced out.
The details remain sketchy. An intruder entered by cutting a padlock on a gate and breaking a museum window, the Paris prosecutor's office said. The museum's security system, including some of the surveillance cameras, had been broken for the past few days, according to a police official. Christophe Girard, deputy culture secretary at Paris City Hall, confirmed that the security system was disabled at the time of the theft, and said a single masked intruder was caught on a video surveillance camera in the early hours of yesterday morning. He said three guards were on duty overnight but "they saw nothing".
The thief – or thieves – also made off with Georges Braque's L'olivier près de l'Estaque (Olive tree near Estaque, 1906), Amedeo Modigliani's La femme a l'éventail (Lady with Fan), and Fernand Léger's Nature morte au chandelier (Still Life with Chandelier, 1922).
The head of the neighbouring gallery, the Palais de Tokyo, Pierre Cornette de Saint-Cyr said: "These five paintings are unsellable, so thieves, sirs, you are imbeciles – now return them."
Jean-Marie Baron, a Parisian art critic, told The Independent: "There must have been more than one person involved." He said that while these are very beautiful works of art, they are not the most famous pieces by each artist.
He floated a number of possible hypotheses for the theft. "Firstly, that a collector who wanted the works and asked someone to steal the paintings. Secondly, that this is a very organised group of thieves, who have stolen the paintings and will now sell them to private collectors. In the traditional art markets this would be impossible, but there is now a new source of private collectors across the world, in far afield places such as Kazakhstan or Indo-China, and some of these people are less bothered about the origins of the work."
Mr Baron added: "It will be interesting to find out how much the paintings are insured for: if they are not properly insured it would be a very bad surprise for the museum."
Stéphane Thefo, a stolen art specialist at Interpol, expressed doubt that one person could have pulled off the theft alone. Interpol has alerted its national bureaus around the world to the theft.
"Every time this happens we wonder why, because it is so difficult for [the thieves] to sell them off," he said. "It is the money they want, not the art." He said that, in a 2008 art theft, works were recovered several days later in a car park. "Thieves often panic because they have works that are burning their fingers. Can you imagine carrying round a Picasso?"
Picasso is the world's most stolen artist. In June last year, a sketchbook valued at €8m was stolen from the Picasso museum in Paris. It has not been recovered. In February 2007, two paintings worth nearly £45m and a drawing were stolen from the Paris home of the artist's granddaughter. Police later recovered the art when the thieves tried to sell it.
If the paintings are not found quickly, it could take decades for them to be recovered – if they ever are. In a similar theft that took place at Boston's Isabella Stewart Gardner Museum in 1990, the 13 works of art stolen are yet to be recovered.