Works by Pablo Picasso, Claude Monet and Henri Matisse were among seven paintings stolen in an early-morning heist at Rotterdam's Kunsthal museum in the Netherlands. The theft occurred around 3a.m. local time, and "initial investigations show the burglar was well prepared," according to a police statement.

The museum's security system, said to be state-of-the-art, is fully automated, relying on security cameras and an alarm system rather than security guards. As is common among cases of art theft, an inside job is suspected. Police are currently reviewing security footage and seeking out witnesses.

The stolen works, described by Chris Marinello of the Art Loss Register to the Associated Press as constituting "one hell of a haul," are Picasso's Harlequin Head (1971), two 1901 Monet canvases (Waterloo Bridge, London and Charing Cross Bridge, London), Matisse's Reading Girl in White and Yellow (1919), Paul Gauguin's Girl in Front of Open Window (1898), Meyer de Haan's Self-Portrait, (ca. 1890) and Woman with Eyes Closed, a 2002 painting by Lucian Freud.

Although such works would fetch millions of dollars at auction, the stolen paintings will be impossible to unload through legitimate channels, given their high profile, and a sale on the black market is likely to bring in only a fraction of the paintings' real value. Alternately, the robbers may attempt to exchange the paintings for ransom money, says Marinello.

The Kunsthal, which lacks a permanent collection, had organized the exhibition of artwork belonging to the Triton Foundation, entitled "Avante-Gardes," as part of the museum's 20th-anniversary celebration. Including over 150 works by artists such as Alexander Calder, Jasper Johns and Andy Warhol, the show marks the first time that the Triton Foundation's collection, amassed by millionaire Willem Cordia (1940-2011), has been exhibited publically as a group. "Avante-Gardes" opened Oct. 7 and was set to run through January 2013.

The Netherlands has not seen an art crime of this magnitude since 1991, when 20 paintings were stolen from the Van Gogh Museum, Amsterdam, only to be recovered 35 minutes later in an abandoned car.