German rider Tony Martin started Thursday's sixth stage in the lead and ended it in the hospital after breaking his collarbone in a crash that he caused near the finish line. He became the second race leader to pull out of the race, after Swiss rider Fabian Cancellara fractured two vertebrae in his lower back on Monday.
"The collarbone is in lots of pieces, so it was a major impact," Martin's Etixx Quick-Step team doctor Helge Riepenhof said. "One of the pieces came through the skin, which means it's an open fracture."
The crash also dragged down defending champion Vincenzo Nibali and fellow Tour contender Nairo Quintana, but they escaped with cuts and bruises. Czech rider Zdenek Stybar rode away amid the chaos to clinch his first Tour stage win.
While neither Martin nor Cancellara was a contender for the overall victory, the injuries they sustained highlight how tough this Tour has been already — and the battered riders haven't even reached the mountains yet.
There was intense heat on day 1, ferocious side winds on day 2, a huge crash on stage 3, scary cobblestone sections on stage 4, and lashing rain on stage 5.
And on the sixth day, another crash.
"This has been like a movie, an emotional roller coaster at this Tour," Martin said.
Frenchman William Bonnet injured his neck after causing Monday's crash, which brought down 30 riders, while Australian rider Michael Matthews finished Thursday's ride despite having two broken ribs sustained on the third stage. He is in last place overall.
With Martin out, 2013 Tour champion Chris Froome moves into the overall lead. The Briton may elect not to wear the yellow jersey on Friday — a sign of respect toward Martin under cycling's etiquette guidelines.
And he may be better off without it.
Martin, his yellow jersey shining, moved near the front during the final kilometres in order to put teammate Mark Cavendish in a good position to attack.
He lost control of his bike with about 900 metres to go. It swerved to the right, clipped another bike and then brought down some eight other riders.
Moments later, he was sitting against a railing, staring into space as the dazed riders looked around for their bikes.
Unable to hold his handlebar, with his left arm in a sling position, Martin rolled slowly over the line with several teammates alongside him.
Two-time Tour champion Alberto Contador of Spain and Froome have escaped all the crashes — although the British rider almost fell when Nibali's bike swerved into his.
In the confusion, Nibali actually thought Froome was to blame.
Then, after Froome came to Nibali's Astana team bus to clear things up, the Italian rider performed a swift U-turn and apologized to his Tour rival.
"I was very upset with him. But then, after watching the video I said sorry to him," Nibali said. "I moved right, (into) Froome, thought it was his fault. Did we clear it all up? Yeah. We are not footballers, we are cyclists."
With bikes piled up and riders slowing down, Stybar rode ahead while Martin sat up on the side of the road.
"I don't get it yet that I have won a stage on the Tour," said the 29-year-old Stygar, a former Cyclo-cross rider who is Martin's teammate.
"It's an amazing feeling, but on the other hand I feel really sorry for Tony," Stygar said. "It's the Tour de France; it's just crazy, crazy. You don't know what will happen around each corner."
Peter Sagan of Slovakia, chasing a fourth straight green jersey as the Tour's best sprinter, finished in second place, two seconds behind.
Quintana had blood dripping from his right arm and elbow as he crossed the line. Froome was relieved to come through the melee with just a minor graze to his knee.
Froome leads Contador by 36 seconds; Nibali by 1:38 and Quintana by 1:56.
Eritrean rider Daniel Teklehaimanot became the first African to seize the polka-dot jersey for best climber after scoring points while part of an early three-man breakaway.
"It's huge for African sport," said Teklehaimanot, the first rider Eritrean to ride in the Tour.
Friday's seventh stage is another for sprinters. It starts from Livarot in the Normandy region — home to a cheese of the same name — and ends 190.5 kilometres (118 miles) later in Fougeres, nestled in the Brittany region.
AP Sports Writer Samuel Petrequin contributed to this report.