Armed robbers have stolen at least 80m euros ($102m, £70m) worth of jewels from one of Paris's most prestigious jewellery shops, police say.
As many as four robbers, two disguised as women, stormed Harry Winston's store near the Champs-Elysee and stole nearly all its valuables.
They spoke French and another language, seemed well informed and knew the names of some of the staff, police say.
The store was hit by another robbery almost 14 months ago.
Armed robbers then stole an estimated 10m euros ($13m) worth of valuables.
The BBC's Alasdair Sandford, in Paris, says the latest robbery is one of the country's most serious for decades.
Around 10 people and 15 staff were in the store on Thursday afternoon when the robbers entered.
Police said some were disguised as women and appeared to know their way around - addressing some of the staff by their names and identifying where stock not on display was being stored.
Once inside they brandished handguns and acted quickly and violently, rounding up staff and customers, our correspondent adds.
They overturned display cases and emptied the shop of nearly all its stock. Some of the staff were said to have been hurt in the robbery.
Harry Winston is situated on the fashionable Avenue Montaigne and attracts a wealthy clientele from around the world, from royalty to film stars.
The company said in a statement: "We are co-operating with the authorities in their investigation.
"Our first concern is the well-being of our employees."