A 1,300-diamond tiara and emerald and sapphire jewellery sets are among the items stolen from the Louvre in Paris in a daylight operation that took just minutes.
Here is what we know about how the heist unfolded and what items have been stolen.
How did the Louvre heist go down?
The thieves struck about 9:30am, local time, when the museum had already opened its doors to the public.
Several intruders used a crane via the riverfront to target the Apollo Gallery where the Crown Diamonds are displayed, including the Regent, the Sancy and the Hortensia.
They forced a window, cut panes with a disc cutter and went straight for the glass display cases, Paris prosecutor Laure Beccuau said.
One of the thieves was wearing a yellow high-vis vest, resembling a construction worker, which investigators have since recovered.
Alarms brought Louvre agents to the room, forcing the intruders to flee. But the theft was already done.
The robbery took between six and seven minutes and was carried out by four people who were unarmed but threatened the guards with angle grinders, Ms Beccuau said.
The robbers tried and failed to set fire to the crane, mounted on the back of a small truck, as they fled on motorbikes, officials said.
The theft unfolded just 250 metres from the Mona Lisa.
What did the Louvre robbers steal?
A total of nine historic jewels were targeted by the criminals, but only eight were actually stolen.
The collection includes pieces owned by former Emperor Napoleon, his nephew Napoleon III, and their wives, the empresses Marie-Louise and Eugénie.
The diamond brooch of Empress Eugénie, worn during a visit by Queen Victoria in 1855.
A necklace and earrings from the sapphire jewellery set of Queen Marie-Amélie and Queen Hortense.
The emerald necklace and earrings from the Marie-Louise set, offered by Napoleon to Marie-Louise on the occasion of their marriage in 1810.
A brooch known as the Reliquary Brooch and a tiara of Empress Eugénie were also stolen.
The thieves apparently dropped a crown made of gold, emeralds and more than 1,300 diamonds as they made their getaway.
The crown of Empress Eugénie was later found broken outside the museum.
"It's worth several tens of millions of euros, just this crown. And it's not, in my opinion, the most important item," Drouot auction house president Alexandre Giquello said.
Ms Beccuau said it was a mystery why the thieves did not steal the Regent Diamond, which is housed in the Apollo Gallery and is estimated to be worth more than $60 million by Sotheby's.
"I don't have an explanation," she said. "It'll only be when they're in custody and face investigators that we'll know what type of order they had and why they didn't target that window."
What's next?
A probe is underway by a specialist unit that has a high success rate in cracking high-profile robberies, Interior Minister Laurent Nunez said.
Investigators were keeping all leads open, Ms Beccuau said.
But she said it was likely the robbery was either commissioned by a collector, in which case there was a chance of recovering the pieces in a good state, or undertaken by thieves interested only in the valuable jewels and precious metals.
She said foreign interference was not among the main hypotheses.
"We're looking at the hypothesis of organised crime," she said.
"Nowadays, anything can be linked to drug trafficking, given the significant sums of money obtained from drug trafficking."
The robbery raises questions about security at the museum where officials had already sounded the alarm about lack of investment at the world-famous site, home to artworks such as the Mona Lisa, that welcomed 8.7 million visitors in 2024.
ABC/wires
