Kim Kardashian West was robbed at gunpoint at a luxury residence in Paris by at least two men dressed as police officers, her publicist and police say.
A police spokesman said the haul from the robbery, mostly jewellery, was worth up to €6 million (£5.2m; $6.7m).
The concierge led the gunmen to the residence where they tied Kardashian West up in the bathroom, police said.
A spokeswoman for the reality TV star, who is 35, said she was "badly shaken but physically unharmed".
Reports say the star has now left France, flying out of a Paris airport aboard a private jet.
Ina Treciokas told CNN the robbery was carried out by two masked men with guns. Police sources told the Associated Press news agency that they were seeking five assailants, two of whom had forced their way into the house.
A jewellery box containing valuables worth €6 million was stolen, as well as a ring worth €4 million, AP reported, citing police officials.
The robbery took place at about 02:30 local time (00:30 GMT), police said.
Kardashian West`s husband, the rapper Kanye West, was on stage at the Meadows Music and Arts Festival in New York at the time of the robbery. He abruptly ended his set, telling fans: "I`m sorry, family emergency. I have to stop the show."
Kardashian West stayed at the luxury residence, behind Paris`s Madeleine church, at least once before, in 2014 before her marriage to West.
"The loss amounts to several million euros, mostly jewellery. The total amount is still being evaluated," police said.
TV host James Corden criticised those making light of the incident. He tweeted: "People making jokes about Kim Kardashian tonight would do well to remember that she`s a mother, a daughter, a wife, a friend. Be nice or shut up."
It is unclear if the couple`s two children, three-year-old daughter North and 10-month-old son Saint, were at the home at the time. Police were guarding the site on Monday.
The star was in Paris for the city`s fashion week with her mother Kris Jenner and her sister Kendall Jenner.
Last week she was approached by a prankster who tried to kiss her bottom but was stopped by a bodyguard.
Kardashian West first rose to fame as a friend and stylist to Paris Hilton. She later appeared in her own reality programme, Keeping up with the Kardashians, about her family.