Stage five of the Criterium du Dauphine was neutralised on Thursday following a large crash involving the peloton.
Race leader Remco Evenepoel was among the riders to suffer injuries.
The stage was cancelled with about 21.5km remaining, with organisers attributing their decision to a lack of available medical staff.
"Due to the fact there are no ambulances to take care of the riders, because they are all busy going to different hospitals, the race will be neutralised," race organisers said.
Tour de France contender Primoz Roglic also fell, but got up quickly and appeared relatively unhurt.
Organisers said riders will ride to the finish together, with no stage winner and no times taken for the day.