The incident occurred around 2pm when a 61-year-old man and a companion were driving a team of two horses, pulling the cart in Tentingen, cantonal police said.
To allow a truck to pass near the entrance to a forest, the cart driver pulled over to one side and drove up a slight slope, police said in a news release.
As a result, the wagon lost balance and toppled to one side, the release said.
The horses were startled by the impact of the wagon and dragged it a short distance before breaking loose and bolting along the Nessierastrasse in the direction of Stersmühle, police said.
The escaped horses then ran into a 14-year-old moped driver, who was injured and needed medical attention.
Ambulance attendants took three of the children to hospital and checked the other occupants of the vehicle who luckily escaped serious injury, police said.
The other children were handed over to their parents, some of whom sought family doctors to care for their offspring.