Paintings by Picasso, Matisse, and Monet are among several stolen from a Dutch art gallery in Rotterdam.
The theft at the Kunsthal museum is one of the largest in years in the Netherlands, and is a stunning blow for the private Triton Foundation collection, which was being exhibited publicly as a group for the first time.
The collection was on display as part of celebrations surrounding Kunsthal's 20th anniversary.
IN PICTURES: Famous art heists
Police spokeswoman Willemieke Romijn said investigators were reviewing videotapes of the theft, which took place around 3 a.m. local time, and calling for any witnesses to come forward. Police have yet to reveal how the heist took place.
The stolen works were Picasso's 1971 "Harlequin Head"; Monet's 1901 "Waterloo Bridge, London" and "Charing Cross Bridge, London"; Henri Matisse's 1919 "Reading Girl in White and Yellow"; Paul Gauguin's 1898 "Girl in Front of Open Window"; Meyer de Haan's "Self-Portrait," around 1890, and Lucian Freud's 2002 work "Woman with Eyes Closed."