We don't know the exact circumstances, but 6 bikes all crashing suggests no distance between them. Frontal damage to the car suggests bikes crashed head on or swerved to avoid and hit the wall...but in the photos it is on its correct side of the road.. Exactly why hard to say , but looking at the tight bend, one or all parties were on wrong side of road. 6 bikes going down a narrow road should have been strung out , so unlikely if that so, why all 6 crashed...
The only lesson I take from this is don't ride in tight groups, and always ride for yourself....give enough room to be able to stop etc. TBH speed wasn't necessarily high for this type of accident to happen...its likely to be road positioning and too close together.
Tragic all the same...