One 14-year-old girl suffered life-threatening injuries in the Emsland region after the horses were spooked when one rider apparently dropped a burning torch on the ground.
This caused the animals to panic and throw off the children riding them, according to the police in Lingen.
The ensuing chaos left scores injured and 44 people were taken to the hospital. Doctors said the most seriously hurt girl was in stable condition by midday Friday.
The youths were guests at a holiday stable in Lathen and had been accompanied by several adults. State prosecutors are not investigating the incident.
All of the skittish horses have since been rounded up.