French rider Julian Alaphilippe of Team Quick-Step won Stage 16 of the Tour de France after the race was disrupted for 15 minutes by protesters.
Riders, including overall leader Geraint Thomas, were hit as police aimed tear gas and pepper spray at protesters who were blocking the road.
Despite finishing around 9 minutes behind Alaphilippe, Thomas retains the yellow jersey, maintaining his 1 minute and 39 second advantage over teammate Chris Froome in general classification.
The 218-kilometer stage from Carcassone to Bagnères-de-Luchon in the southwest of France was the first to hit the Pyrenees mountains, and was packed full of incidents.
Less than 30 kilometers into the stage, a protest by French farmers brought to the riders to a halt after bales of hay were thrown onto the road. The protesters were arrested and police used pepper spray and tear gas, which inadvertently blew into the faces of some of the riders.
Thomas and green jersey wearer Peter Sagan were some those seen washing their eyes after the incident, which brought the race to a stop for 15 minutes.
After the break, the peleton split into two. Crucially for general classification leader Thomas, none of his yellow jersey contenders were involved in the breakaway. Out of the pack, Greg Van Avermaet was the highest-ranked, but was still 18 minutes behind overall.
As the Tour reached the mountains of the Pyrenees, Philippe Gilbert and Alaphilippe led on the ascent to Col de Portet-d'Aspet.
Gilbert reached the top first but had a horrific crash on the way back down, losing control of his bike and flipping over a roadside wall.
The Belgian rider was able to continue with the race but was overtaken by the entire breakaway group as he got back to his feet.
Alaphilippe pressed on and was first to reach the top of the category one climb to Col de Mente. The French rider also extended his lead at the top of the King of the Mountain standings to 49 points.
The 17-man breakaway group were 10 minutes ahead of the peleton going into the final 8-kilometer climb to Col du Portillon, with Guy Martin, Thomas Yates and Pierre Latour joining Alaphilippe.
In the end it was British rider Yates who won the climb to Col du Portillon, and looked set to win his first Tour stage.
But with only 5 kilometers of descent to go, Yates crashed turning a corner and could only watch as Alaphilippe flew past.
It was a gift, but Alaphilippe didn't care as he cruised to his second stage win of this year's Tour.
1. Julian Alaphilippe (FRA) Quick-Step Floors 5:13:22
2. Gorka Izagirre (ESP) Bahrain - Merida +15
3. Adam Yates (GBR) Mitchelton - Scott "
4. Bauke Mollema (NED) Trek - Segafredo "
5. Domenico Pozzovivo (ITA) Bahrain - Merida +18
1. Geraint Thomas (GBR) Team Sky 68:12:01
2. Chris Froome (GBR) Team Sky +1:39
3. Tom Dumoulin (NED) Team Sunweb +1:50
4. Primož Roglic (SLO) Team LottoNL - Jumbo +2:38
5. Romain Bardet (FRA) AG2R La Mondiale +3:21
More to follow