Armed robbers who used explosives to break into a gold refining laboratory in Lyon last week made off with metals worth around €28 million, all of which police recovered shortly afterwards, a French prosecutor said.
The raid in the eastern city took place on Thursday last week, with police swiftly arresting the suspected perpetrators and seizing 306 kilograms of precious metals, mostly gold.
Six people - five men and one woman, aged from 30 to 40 - were detained shortly after the incident at Pourquery Laboratories, Lyon prosecutor Thierry Dran said during press conference.
"These are seasoned criminals," he said. The five men have previous convictions, three of whom for armed robbery.
The woman, who has no criminal record, and one of the men denied involvement, while the other four remained silent during questioning, the prosecutor said.
Mr Dran said he had requested they be charged with several offences, including criminal conspiracy and robbery with violence, and placed in pre-trial detention, though it was not immediately clear if all six would face the same charges.
Officials had initially valued the haul at €12 million, but Mr Dran said its true worth was €28 million - more than double that amount.
The attack at the gold lab is the latest in a string of thefts that have stoked concern about inadequate security at France's museums and other places holding high-value items.
In one video posted on social media, a witness -- apparently an employee at a neighbouring company - can be heard alerting the emergency services, saying he and his colleagues had heard a "huge explosion" and the robbers carried "Kalashnikovs".
Police arrested the suspects less than two hours after the robbery, seizing assault rifles, handguns and explosives in addition to the stolen loot.
Five employees of Pourquery Laboratories were "slightly injured in the explosion" and three were taken to hospital for checks.
The heist occurred on the same day French police arrested five more people, including a prime suspect, over last month's brazen Louvre museum heist.
But small-time criminals are believed to be behind the jewellery theft from the world's most visited art museum, the top Paris prosecutor has said.
In another high-profile incident, thieves last month broke into the French capital's Natural History Museum, making off with gold samples worth more than €1 million.
A 24-year-old Chinese woman was arrested earlier this month in Barcelona over the break-in and theft, prosecutors said.
