A touch of wheels in the final bunch sprint created a chain reaction on the left-hand side with multiple riders cannoning into the barriers and others going to the ground.
Few riders in the peloton were able to avoid the carnage with the force of the collision collapsing the barriers.
No more than 20 riders were able to escape the crash with most of the bunch caught up in the incident.
Riders from a number of teams were taken away from the scene on stretchers with Noah Granigan, Hijiri Oda and Manuel Belletti requiring neck braces.
Belleti's team Eolo-Kometa revealed he avoided fractures, while Nippo-Provence-PTS announced their rider Oda was also free of any serious injury.
Alpecin-Fenix have reported that Alexander Kreiger has been taken to hospital for further examinations, while Juan Jose Lobato was also cleared of serious injury by team Euskaltel-Euskadi
Stage five of the Tour of Turkey continues on Thursday night (AEST)
