Three suspects were quickly arrested near the chic Place Vendome in central Paris, but at least two others got away, a police official said. Some of the jewellery has been recovered.
Armed robbers launched a spectacular raid on the world-famous Ritz hotel in Paris on Wednesday, making off with an estimated $4.75 million worth of jewels, the latest in a string of high-profile heists in the French capital.
The gang of five men armed with hatchets smashed display windows on the ground floor of the hotel in Paris' luxurious Place Vendome around 1730 GMT, making off with the jewels.
Three of the gang were detained while fleeing the scene and some roads around the hotel were sealed off by security forces following the incident. Two people were still being sought by authorities on Thursday evening.
TRT World's Nafisa Latic has more.
"We heard a loud noise and lots of racket in the street," one hotel employee said.
"Passers-by took refuge in the hotel. We didn't know what was going on until someone told us there had been a robbery."
Another employee said he saw a motorbike speed along a road at the back of the hotel after the break-in.
As many of you know my parents and I are currently in Paris. There was a shooting at the bar we were at in the Ritz-Carlton hotel involving 4 robbers. They ran through the bar and started shooting at the bar adjacent to us. My parents and I are safe thanks to the wonderful staff.— Nik (@Nikilazar20) January 10, 2018
Several luxury brands display their jewels in the street-front windows of the Ritz.
A judicial source put the value of the jewels seized at "more than four million euros" ($4.75 million).
However, a police source said that police had recovered some of the loot.
Part of the loot was recovered after being scattered about during the arrest of the three suspects.
More jewels and watches were found in a bag dropped by one of the two robbers who got away, another source added, without being able to give an estimate for the value of the goods retrieved.
The three men arrested, all around 30 years old, are from the Seine-Saint-Denis area north of Paris, and are "well known to the police for armed robbery, violence and receiving stolen goods", a source close to the inquiry said.
The suspects were wearing gloves and balaclavas and carrying handguns as well as hatchets, according to police sources.
On finding their escape route blocked they tried to transfer the loot through a window to the two accomplices waiting outside.
One of the two accomplices fled by car, while the other made a getaway on a motorbike, dropping a bag of jewels in the process.
On Thursday, the source close to the inquiry said the car had been found in the Val d'Oise department, near Seine-Saint-Denis.
The hotel's management has declined to comment on the robbery.
Paris prosecutors have opened a probe into the robbery, according to a judicial source.
Riches and robbers
Place Vendome, with its opulent window displays of jewellers and high-end watchmakers, has been the scene of several audacious daytime raids.
Security had been boosted in the area, which also houses France's justice ministry, in 2014 after several daring armed raids on Place Vendome in which jewels worth between $372,000 and $2.4 million were seized.
But thieves struck again in March 2016, when an estimated $6.5 million (six million euros) worth of jewels were stolen from luxury fashion brand Chopard by robbers who threatened employees with a gun and grenade. Three men were charged in connection with that heist.
The French capital's most high-profile recent jewellery theft was carried out in October 2016 against US reality television star Kim Kardashian.
Five men, some wearing jackets with police insignia, held Kardashian at gunpoint, making off with several pieces of gold and diamond jewellery as well as a ring – a total estimated worth of $10.75 million.
One of the robbers, fleeing the scene on a bicycle, dropped a diamond-encrusted cross worth $26.565, which was found by a passer-by a few hours later.
It remains the only piece to be recovered from the heist.
The landmark Paris Ritz hotel re-opened its palatial doors to guests in 2016 after nearly four years of renovations and a major fire.
The hotel founded by Swiss entrepreneur Cesar Ritz in 1898 is storied as the lodging of choice of Charlie Chaplin, Coco Chanel and Ernest Hemingway, who has a small bar named after him.
In more recent history however, the Ritz has become known as the place where Britain's Princess Diana spent her last hours before a car accident in a tunnel in the French capital while being pursued by paparazzi.