The robbers stole the paintings on Sunday from the E.G. Buehrle Collection
, one of Europe's finest museums for Impressionist and post-Impressionist art, police said.
One of the men threatened personnel at the museum's front door with a pistol. The two other robbers entered the exhibition room and stole the four oil paintings.
Afterward, the men loaded the paintings into a white car parked in front of the museum and drove off. Police asked for witnesses to come forward. It is possible that the paintings were partly sticking out of the vehicle as the robbers made their getaway.
A reward of about $90,000 was offered for information leading to the recovery of the paintings â€” Claude Monet's "Poppy field at Vetheuil," Edgar Degas' "Ludovic Lepic and his Daughter," Vincent van Gogh's "Blooming Chestnut Branches," and Paul Cezanne's "Boy in the Red Waistcoat."
The paintings were hung behind glass and the security alarms went off as soon as the paintings were removed.
This art heist follows a recent theft in Switzerland
of two Pablo Picasso paintings. Swiss police reported two oil paintings that were stolen from an exhibition near Zurich.
The FBI estimates the market for stolen art at $6 billion annually, and Interpol has about 30,000 pieces of stolen art in its database. While only a fraction of the stolen art is ever found, the theft of iconic objects, especially by force, is rarer because of the intense police work that follows and because the works are so difficult to sell.