The gathering comes as the French Parliament is seeking to tighten legislation against unauthorised rave parties, introducing prison sentences for organisers and fines for attendees.
“Despite its illegal nature, the Government has mobilised to ensure the safety of this event and limit any disturbances,” the prefecture said.
Philippe Le Moing Surzur, the local prefect, said the site was “extremely dangerous due to the unexploded ordnance it may contain”.
While modern shells posed no threat, he warned of the risk from older unexploded ordnance dating back to World War II.
Old artillery shells
He said that even France’s Directorate General of Armaments, which owns the land, did not have precise knowledge of the risks.
“This is a site that has been in use for 150 years, and we know there are potentially old artillery shells there,” he said, adding that bomb disposal experts discover them regularly.
The firing range covers 10,000ha and is crisscrossed by roads that are closed during tests but open to the public at other times.
Signs prohibit access to the range itself, but it is not fenced off.
The organisers have urged attendees to refrain from lighting fires, digging or picking up any objects.
The local mayor’s office said residents and partygoers were getting on well.
“For once there’s something going on, make the most of it!” Paulette, 64, who lives in the village nearby and declined to give her family name, told AFP.
Emergency services treated 12 people with minor injuries.
The prefect said one person had been struck by a vehicle, and a number of the injured people had cut themselves while handling sharp shrapnel.
Revellers see the giant party not only as a chance to unwind, but also as a protest against the rave-curbing legislation.
“It’s a way of showing that participants are mobilised and will keep coming, whatever happens, and will continue to challenge these laws,” a member of the Tekno Anti Rep collective told AFP.
Message against repression
A free party is usually an illegal form of rave rooted in anti-establishment culture.
They are held without permission in remote locations, and admission is free or by donation.
“I had heard there were going to be a lot of people, but once you’re there, it’s still a shock to see so many people gathered in one place,” said one 22-year-old man, who did not want to be named.
Another partygoer, 19, also anonymous, said the turnout was “a strong message against repression”.
Around 600 police and 45 firefighters were deployed at the site.
“We’re getting ready for a big get-together tonight,” Edith Raquin, the Mayor of Cornusse, a village of 220 people located less than 2km from the site, said.
She said that the revellers came across as “peaceful people” and some elderly residents were “delighted” to talk with them.
“They are polite, they say hello,” Raquin said.
– Agence France-Presse