In a school in Limburg, Hesse, 17 people were injured by irritant gas on Monday afternoon.
Ambulance service, fire brigade and police were called because several students in a class complained of respiratory problems.
On site, the officers were able to determine that irritant gas had been sprayed in a classroom.
After initial investigations, a youngster apparently misinterpreted a classmate's irritant gas can as a deodorant and sprayed himself with it, the police said.
Seven ambulances in action
Ten people had to be taken to a hospital for treatment.
The rescue service was on duty with seven ambulances and two emergency doctors, and the fire brigade provided additional support.
Police investigations are continuing.
The school administration informed the parents of the pupils concerned.
kfr