The crash saw several favourites including Alejandro Valverde (Movistar) and Tadej Pogačar (UAE Team Emirates) go down, while sprinter Luka Mezgec (Mitchelton-Scott) was the worst off, being taken to hospital in an ambulance.
The Australian team later confirmed that Mezgec had suffered a fracture to his hip.
"Luka has fractured the iliac crest on his right hip," said Mitchelton-Scott's team doctor. "Thankfully he has avoided damage on the joint so it’s not considered a bad fracture.
“He will not need surgery, but will need to spend a period of time laying down, normally between one and three weeks depending on the speed of his recovery. He will not be required to spend this period in hospital, so we will transfer him home via ambulance.”
Valverde came down in the crash but was calm after the finish.
"It was an uphill sprint finish, and with all that speed and tension, two riders touched wheels and we all went down," Valverde said.
"I'm OK, my wrist hurts a bit, but it wasn't so bad. I hope it doesn't affect me for the stages to come."
Pogačar, currently sitting third overall, had some skin off and was bleeding at the elbow when he crossed the finish line, but the 20-year-old was more concerned for others than himself.
"I didnt' expect so much stress today but the crash was a pretty hard one," said Pogačar. "I don't know what happened, but suddenly half of the group was on the ground. I hope everyone is OK, and no serious injuries are sustained by anyone."
Race leader Primoz Roglic (Jumbo-Visma) finished the stage safely and retained the race lead.