About 15 armed assailants attacked two vans carrying millions of euros worth of jewels on a French highway on Wednesday, forced out the drivers and sped away, according to police.

Gendarmes and other authorities are combing the Burgundy region southeast of Paris for the attackers, after the latest in a string of big jewel heists in France in recent years.

No one was injured in the attack on the A6 highway connecting Paris and Lyon, and the drivers of the two vans were left at the scene unharmed, a police official said. The perpetrators escaped in four cars and the two vans, which police found burned and abandoned in a forest near the site of the attack, the official said. The jewels remain missing.

The official spoke on condition of anonymity because he wasn’t authorised to be publicly named.

In November, two gunmen robbed a Cartier jewellery boutique in a tony and tourist-filled Paris neighborhood, fled police in a chase across the Seine River, took a hostage and then surrendered.

In 2013, the Cannes Film Festival was hit by two high-profile thefts. First, a gunman walked into a jewel show at the Carlton International Hotel, stole $136 million in loot, and disappeared down a side street. Then, two armed men made off with a haul of luxury watches on the same promenade.

Last month, eight people were convicted in connection with one of the most spectacular jewel thefts in recent French history at a Harry Winston boutique in Paris. In the 2008 hold-up, three cross-dressing gunmen stole about $92 million in goods.