Paris ? It was nightfall in Paris, Christmas lights sparkled and among shoppers on one of the French capital’s ritziest streets was a small group who headed toward the luxury Harry Winston jewelry boutique. Once inside, they transformed into gunmen and pulled off one of the most spectacular jewel heists in history.

On Friday, the Avenue Montaigne, just off the Champs-Elysees, maintained its discreet, moneyed air. The only signs of the lightning-fast armed robbery were three empty display windows. And the locked doors.

The thieves vanished with $108 million worth of jewels — just over a year after a similar heist there.

The four gunmen — three of whom wore wigs and women’s clothing — forced employees to strip rings, necklaces and earrings from window displays and pull more out of safes, said Isabelle Montagne, spokeswoman for the Paris prosecutor’s office.

The brazen robbery early Thursday evening took place in the presence of security guards and security cameras in one of Paris’ toniest shopping locales. Besides Harry Winston, Nina Ricci, Gucci, Chanel and Dior are among the fashion houses with boutiques on Avenue Montaigne.

The robbers threatened the 15 employees with handguns and hit some on the head, according to a police official who cannot be identified under agency policy. The robbers spoke a foreign language at times and appeared to know employees’ names, the official said.

Montagne said there was only one client in the store at the time, and no one was injured and no weapons were fired. She called the incident “very well-organized.” Security guards are banned from carrying guns in France.

Investigators seized the store’s surveillance tapes, and police said one group under suspicion was the so-called “Pink Panthers,” a ring of jewel thieves mostly from the former Yugoslavia. The international police agency Interpol has blamed the gang for jewel thefts in 19 countries in Europe, Asia and the Persian Gulf worth more than $150 million over the past 10 years.

Paris’ Harry Winston boutique was targeted in a heist in October 2007, when three thieves made off with $28.4 million worth of jewels after forcing employees to open safes. They were never caught.

French police called Thursday’s robbery one of the world’s costliest jewel thefts.

The Paris robbers chose one of the world’s most glamorous targets: Harry Winston jewels have adorned Queen Elizabeth, Elizabeth Taylor, Madonna and numerous Hollywood celebrities.

The jeweler is famous for its one-of-a-kind diamond-studded pendants, opulent chandelier earrings and colored diamonds in vivid shades of yellow, blue and pink.

Geoff Field, CEO of the British Jewelers’ Association, called it a “pretty sensational” robbery, but added: “There are well-known gangs around looking to target high-value diamonds.”

He stressed the stolen jewels would be difficult to sell “through any legitimate channels.”