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.
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."