The collapse took place at around 5PM. The school's owner told initially Yle that at the time of the collapse, four people, as well as horses, were in the building.
One adult who was rescued, was serious injured, but not critically.
Three children rescued from the building have also been hospitalized, one with serious injuries. The other two sustained minor injuries.
Fifteen emergency units, six paramedical units and a rescue helicopter were at the scene, as was a mobile crane.
The 1700 square metre riding arena was built in the late 1980s. It is believed that the roof of the wooden structure collapsed under the weight of snow.