The Jerez Moto2 race has been red flagged on the second lap after a fluid spillage caused eight riders to fall.
Shoya Tomizawa crashed first, seemingly falling due to contact with Simone Corsi as they battled for the lead into the hairpin at the end of the back straight.
In his wake, fourth and fifth-placed Toni Elias and Julian fell on their own having suddenly lost grip, with a further five bikes then doing likewise as they seemed to hit oil or water on the surface.
Despite many bikes and riders clattering into each other in the gravel trap, everyone involved appeared to escape injury and most should be able to take the restart.
The race will now be shortened from the planned 26 laps to 17, with a restart set for 12.45pm local time.