PARIS (NYTIMES, REUTERS, AFP)- Just after midnight on Monday, Kim Kardashian West left an intimate Fashion Week reception and dinner in the Marais section of Paris, at which truffled scrambled eggs, white fish and copious amounts of Champagne were served. She had just attended a Givenchy fashion show with her sister Kourtney, their mother Kris Jenner and rock singer Courtney Love.

With Kourtney, Kardashian West posed for some paparazzi waiting outside. Along with a bodyguard, they entered a dark van with tinted windows and drove off.

About 2½ hours later, French officials said, the reality TV star was robbed at gunpoint of jewellery worth at least 8 million euros (S$12.2 million). She was alone in a luxurious apartment in the Eighth Arrondissement, about 3km from the dinner, when two men burst in, tied her up and gagged her, then escaped with at least three accomplices, officials said.

The crime stunned fans of Kardashian West, who has millions of followers on Twitter and Instagram. Her husband, rapper Kanye West, abruptly walked off the stage of a concert in Queens, New York, when he learned of the crime. The crime also focused unwanted attention on France, where tourism has plummeted following a series of major terrorist attacks.

Crucial details remained unclear on Monday, including why Kardashian West was alone and why she was carrying such valuable jewellery. But police officials and the mayor of Paris vowed to get to the bottom of the crime and to reassure their citizens, and foreigners, that the French capital was safe to visit.

"I condemn the attack Kim Kardashian suffered last night in her hotel," Mayor Anne Hidalgo said in a statement. "She has my support and will always be welcome here in Paris. I have full confidence that the police force, as part of their investigation, will quickly identify and apprehend the perpetrators of these acts."

Mr Laurent Riquart, a spokesman for the investigative unit of the Paris police, said the men were part of a group of about five people who stormed the VIP residence, the Hotel de Pourtales, near the Madeleine church. At least one had a handgun.

"Once they were in the building, they tied up the receptionist's hands," he said in a phone interview. "They went up the stairs and entered her room. They tied up her hands and put a gag in her mouth."

Mr Luc Poignant, a spokesman for a police officers' union, said the men locked Kardashian West in a bathroom after tying her up with tape. The robbers took away a box of jewels worth 5 million to 6 million euros and a ring worth about 4 million euros, Reuters quoted an unnammed Paris police source as saying. They also made off with mobile phones and a wallet that contained credit cards.

Three of the men left on foot, and two on bikes, he said. The men had targeted their victim - they forced the concierge to tell them where Kardashian West was staying, and tied his hands.

The men appeared to have worn shirts identifying themselves as police officers - but also balaclavas and gloves, which are not part of the police uniform.

A police source told Reuters that the star, who has two children with West, was not beaten but the robbers put a handgun against her temple before tying her up.

Sources told website TMZ that the star was asleep in a robe when she heard boots pounding up the stairs of the two-storey apartment. She tried to call her security guard Pascal Duvier but her phone was snatched off by one of the men. They also tied up her ankles before putting her in the bathtub.

She told police that she feared she was about to be raped, according to TMZ. The robbers allegedly kept saying "ring, ring". She told them where to find a new ring she had received from her husband - a photograph of which she posted to social media last Friday, TMZ added.

Kardashian West, 35, had posted a photo of the huge diamond sparkler - reportedly a 20-carat ring by Lorraine Schwartz - on her finger, while resting her chin on her hand, mouth opened to show off gold dental grillz, as well as a black and gold choker and, of course, serious cleavage. Reports said it was a second engagement ring West gave in August, worth US$4 million (S$5.5 million).

Meanwhile, her friend Simone Harouche, a stylist, had hopped out of her bed in a bedroom downstairs. She locked herself in a bathroom and called Duvier, who was out providing security for Kourtney at a Paris nightclub. Duvier returned to the apartment two minutes after the robbers left, TMZ said.

E! News, whose United States network broadcasts the Keeping Up With The Kardashians television show, on Monday quoted a source close to Kardashian West as saying she had feared for her life. "She begged for them to let her live and (said) she has babies at home... She thought they were for sure going to kill her," the unidentified source told E! News.

She was "badly shaken but physically unharmed", her spokesman told The Associated Press, offering no further details. She left France on Monday by private jet with her daughter, North, three, and son, Saint, who is 10 months old. The children were not present when the robbery occurred. It appeared that she gave a statement to the police before she departed.

In New York, wearing sunglasses and with her head bowed, she was pictured entering her Manhattan apartment with her husband. She was not wearing her 20-carat diamond ring. She said nothing to waiting media. Her friends turned up at her residence shortly and also avoided talking to the media.

Foreign tourism to France has dropped substantially after major terrorism attacks in Paris in November last year and in the Mediterranean city of Nice in July. France remains under a state of emergency.

High-profile crimes are not uncommon in France, which by many estimates remains the world's most-visited country. In 2013, a thief robbed a luxury hotel in Cannes, on the Riviera, and made off with tens of millions of dollars in jewellery. In 2014, the Place Vendome, one of the most fashionable squares in Paris, was hit by a series of smash-and-grab robberies. Last year, thieves assaulted two armoured vans and made off with jewellery worth an estimated US$10 million.

Only a few days ago, Kardashian West was tackled in a Paris street by a man who was pinned to the ground by her bodyguards. The man, identified as Vitalii Sediuk, had a record for following celebrities around and did not appear to be a robber.