Robbers rammed their car into a mediaeval cathedral in southwest France early Monday, sawing through metal bars to grab silver chalices and other irreplaceable church treasures, according to local authorities.
Initial investigations suggest the gang tied a tree trunk to the front of the car used to smash through a door of the cathedral in the town of Oloron-Sainte-Marie.
The building edifice has been registered as a UNESCO World Heritage site since 1998.
Once inside, the thieves helped themselves to chalices and other ceremonial objects, much of it gold, as well as a 17th-century nativity scene and a collection of clothes.
The treasures had been kept in a chapel, behind a steel grid whose "bars were sawn through," according to local official, Laurent Paris.
Oloron-Sainte-Marie is a favourite stopover for Catholic pilgrims headed for the Cathedral of Santiago de Compostela in Spain. It lies some 50 kilometres north of the Spanish border.
"The mayor was informed at about 2:00 am after locals woken by the noise and the cathedral alarm alerted the police," said Paris.
Witnesses saw three individuals take part in the heist, he added, and is the first time the cathedral had been attacked.
Experts will take stock of the loot taken, but Paris described the loss as "considerable".
"Over and above the monetary value, residents now find themselves cut off from their history and their heritage," he said.
French Culture Minister Frank Riester on Monday condemned the robbery.
"I strongly condemn the attack perpetrated against the Cathedral of Oloron-Sainte-Marie last night and share the emotion of the Catholics of France legitimately shocked by this theft and degradation.
"The authors will be found and punished," he said in a tweet.
The cathedral is best known for one of its oldest remaining features: a Romanesque portal created in the 12th century.
The building had been burned burned down in both the 13th and early 14th centuries. It was pillaged at the end of the 16th during France's religious wars between Catholics and protestant Huguenots.
Repaired and remodelled several times from the middle ages to the early modern era, it was fully restored in the 19th century.