An armed gang has stolen four paintings worth some $160m (£82m) by the great painters Cezanne, Degas, Van Gogh and Monet from a museum in Zurich.
Swiss police said the robbery happened at the Emil Buehrle Collection on Sunday. The three thieves are at large.
The gang threatened a security guard before seizing the works. The art theft is one of the biggest in the world in the last 20 years.
It comes just days after two Picasso paintings were stolen near Zurich.
HOW THE THEFT HAPPENED
1: Zurich police say the three robbers entered the museum just before it shut on Sunday
2: Officers say one of the men used a gun to force 15 visitors and several staff to the floor
3: Police say his two accomplices then seized the four paintings from a ground-floor display hall - according to the museum website, the Music Room
4: Eyewitnesses say the robbers loaded the art into a white vehicle in front of the museum and drove off. It was all over in three minutes, police say
The four paintings stolen on Sunday are: Poppies near Vetheuil, by Claude Monet (1879), Count Lepic and his Daughters, by Edgar Degas (1871), Chestnut in Bloom, by Vincent Van Gogh (1890) and Boy in a Red Jacket, by Paul Cezanne (1888), police said.
A police statement said the three masked men entered the museum in central Zurich at about 1630 local time (1530 GMT).
One of the men threatened staff with a pistol, while the other two collected the paintings, it said.
They were then loaded into a white vehicle parked outside the museum, the statement said.
Police said one of the thieves spoke German with a Slavic accent, and described the robbery as spectacular.
"We're talking about the biggest ever robbery carried out in Switzerland, even Europe," Zurich police spokesman Mario Cortesi told journalists.
Museum director Lukas Gloor said the stolen paintings were "the four finest in the museum's collection", the AFP news agency reported.
MAJOR RECENT ART THEFTS
2007 - Picasso's Portrait of Suzanne Bloch (worth £26m) stolen in Sao Paulo; later found
2004 - Munch's Scream and Madonna (valued at £10m) snatched in Oslo; recovered in 2006
2003 - Da Vinci's Madonna with the Yarnwinder (valued at £30m) stolen in Scotland; found in 2007
2002 - Van Gogh's two works (worth millions of dollars) stolen in Amsterdam
Mr Gloor said the works were so well-known that it would be impossible to try and sell them on the open market.
The famous Emil Buehrle Collection contains some of the world's most important impressionist works, the BBC's Imogen Foulkes in Switzerland says.
Picasso's oil paintings - Head of Horse and Glass and Pitcher - were taken from an exhibition in the town of Pfaeffikon last Wednesday.