A chemical leak at a school in canton Schwyz sent 12 children and one adult to hospital and forced another 60 to be evacuated.
But there have been no reports of significant injuries.
The cause of the poisoning has yet to be determined, but it’s thought it was an ozone leak from a machine used to disinfect the school swimming pool.
Emergency services responded with full force when the alarm was sounded. 200 rescuers, 17 ambulances and 4 helicopters raced to the school in Lachen.
Parents are being told to keep an eye on their children in case of breathing difficulties, those in hospital are not in danger, according to a spokesman.