Four-time champion Chris Froome is among riders whose eyes needed treatment for tear gas when a farmers' protest interrupted the 16th stage of the Tour de France.
Bales of hay blocked the road 30km into the 218km leg from Carcassonne to Bagneres De-Luchon.
Tour organisers said police used tear gas to disperse the protesters as the peloton approached.
Froome, race leader Geraint Thomas, and world champion Peter Sagan appeared to be among those affected by the chemical, and were treated with eye drops.
The stage resumed after a 15 minute delay.
This Tour has been marred by incidents.
Race organisers have struggled to deal with angry fans protesting Froome's participation.
After fans threw flares at riders in the climb to the ski resort of Alpe d'Huez, Tour organisers banned the use of smoke flares for the rest of the race.
Froome raced all season under the cloud of a potential ban for using twice the permitted level of salbutamol during his victory at the Spanish Vuelta in September.
He was cleared only just before the Tour.
He said he has been repeatedly spat at since the race started, and spectators have punched him and tried to make him fall off his bike.
Froome sits second in the general classification, 60.39 seconds behind Sky teammate Thomas.