An ambulance caused chaos and crashes in a peloton when it drove onto the course of the Faun-Ardèche Classic.
A video posted by La Flamme Rouge shows the emergency vehicle approaching the pack head on as it drives around a corner on a narrow stretch of road.
A number of riders hit the deck shortly after although it is not clear from the footage whether any of them actually made contact with the van.
— La Flamme Rouge (@laflammerouge16) February 28, 2021
Posting under the video, La Flamme Rouge wrote: "Why this should never happen because some people don't seem to understand.
"The race is supported by police vehicles to close the road.
"They MUST let jury know if there are any difficulties on the road in closing it down. If jury knows this they they instantly neutralise the race."
Some people however questioned who should have priority on the road in an emergency situation.
One Twitter user wrote: "The UCI has nothing to do with this or the organisation, it is an emergency car.
"Firefighters or ambulance that is passing has priority. It is considered a road accident."
However, La Flamme Rouge, replied: "Just because there's an emergency doesn't mean others lives have to be put at risk.
"The commissaires of the race are UCI commissaires, so yes UCI has a lot to do with it.
"It's above all a race on the UCI calendar."
This year's edition of the French race was won by Groupama-FDJ's David Gaudu with Clément Champoussin of AG2R and Education First's Hugh Carthy completing the podium.