Now that it's obvious Uber is trying to put conventional taxis out of business, the people who drive those cars are more worried than ever. And in Paris, where Uber was recently legalized, that worry just spilled over into street violence.

Le Monde, along with Twitter reports, say a 5,000 strong strike against "unfair competition" has turned into a window-smashing, tire-slashing surge against the smartphone pickup service:

The Verge describes an attack encountered by Renaud Visage, above:

Renaud Visage, photographer and CTO of Eventbrite, was traveling in the car with Borlongan, and corroborated her reports in a phone interview. Visage says taxis blockaded one of the main highways from the airport, forcing cars to file through a single lane. When their van passed through the checkpoint, "three or four" men on each side started throwing rocks and paint at them, shattering the back window and leaving the passengers with cuts on their hands. At a second blockade, an assailant slashed the back tire, forcing them to pull off the road a few minutes later.

Ain't no labor strike like a Parisian labor strike, but it's a safe bet Uber will see more backlash like this as it spreads around the world.