According to the Norwegian Environmental Agency, lightning killed several hundred reindeer.
The herd on Hardangervidda — a mountain plateau — was hit by lightning Friday, August 23, 2016. The herd included males and females, including seventy calves. Most were already dead, with several euthanized.
Representatives from the Norwegian Institute for Nature Research (NINA) were in the area a few days later, and extracted medical samples from the animals.
Average reindeer population on Hardangervidda is around 2,000.
The original Norwegian release is available here.