The crash happened at high speed on the descent from the Olaeta climb with 35.9 km remaining when one rider went down causing a chain reaction, and Vingegaard was still on the ground receiving medical treatment several minutes later.
"The stage has been neutralised. Jonas is on his way to the hospital," Vingegaard's Team Visma-Lease a Bike said on social media platform X. Only the original breakaway of six riders were allowed to contest the stage win.
Vingegaard was taken away on a stretcher wearing a neck brace.
"Examinations at the hospital have revealed that he has a broken collarbone and several broken ribs. He remains in hospital as a precaution," Team Visma-Lease a Bike later said.
Evenepoel's Soudal-Quick Step team said the Belgian had abandoned the race and he was taken to hospital in the team car, with Slovenian Roglic of Bora–Hansgrohe also forced to withdraw.
Soudal-Quick Step later confirmed that Evenepoel had sustained a fracture to his right collarbone and his right shoulder blade and would have surgery on Friday in Belgium.
Australian Jay Vine of UAE-Team Emirates was another rider taken to hospital by ambulance, with his team saying he was conscious and talking.
There were no ambulances left to follow the race and the stage was stopped for an hour before the organisers decided to continue.
"The race is neutralised until the finish line, the six leading runners will compete in the stage but the stage times will not be counted for the general classification. The peloton will go in neutral until the finish line," race organisers said.
South African Louis Meintjes of Intermarche-Wanty won the stage, but his victory was overshadowed by the crash.
"It's not the way you want to win," Meintjes said.
"I felt good and if there was a chance for the breakaway I would have been ready to fight for the stage, but it takes a bit of the pleasure out of it.
"It's maybe a victory but it doesn't really feel like it. You want it to be fair for everyone."
Roglic came into stage four with a seven-second lead over Evenepoel, with Vingegaard a further seven seconds behind in fifth, but with the main contenders out of the race, Dane Mattias Skjelmose of Lidl-Trek now holds the overall lead.
