Complex sentence: Heydrich was first placed in the driver's cab, but after complaining that the truck's movement was causing him pain, he was placed in the back of the truck, on his stomach, and taken to the emergency room at Na Bulovce Hospital.
Split into simpler sentences: Heydrich was first placed in the driver's cab, but complained that the truck's movement was causing him pain. He was placed in the back of the truck, on his stomach, and taken to the emergency room at Na Bulovce Hospital.