A protest by local farmers brought Stage 16 of the Tour de France to a halt on Tuesday as French and British media said bales of hay were thrown onto the road.
Cycling teams and French media said police used tear gas to disperse the protesters, but it ended up blowing in the faces of the riders, which led to the race being stopped.
The race continued after the 15-minute hiatus.
Yellow jersey holder Geraint Thomas and world champion Peter Sagan were among the riders rinsing their eyes after the incident, which stopped the stage for 15 minutes. However there is no indication that the protest was directed at any specific riders.
It is not the first time that protesters have interrupted a prominent race, the most memorable incident happening in the 1984 Paris-Nice, when French great Bernard Hinault punched one of the demonstrators.