Three staff members felt unwell the day before a Perth and Kinross primary school was evacuated due to a suspected chemical leak.
On Wednesday, Crieff Primary School closed its kitchen and pupils were given packed lunches to prevent any illnesses from spreading.
No faults were found when kitchen equipment was tested. But another staff member became unwell the next day and the school was closed and evacuated by police.
Altogether 11 adults were taken to hospital on Thursday. Police have not yet found a spillage or leak that could have led to their illness.
The school is set to reopen on Monday.
Police Scotland said officers were called to the school on Broich Road at about 11:30 on Thursday and the building was cleared as a precaution.
The Scottish Ambulance Service sent four ambulances and three special operation response teams to the school, while the Scottish Fire and Rescue Service (SFRS) sent two appliances and one specialist appliance.
The school was cordoned off and 11 adults were taken to Ninewells Hospitals in Dundee. They were later discharged after a clinical assessment.
An NHS Tayside spokeswoman said none of the patients had any “immediate medical concerns”.
Testing will continue, however, to identify the cause of their symptoms and the primary school kitchen will be deep cleaned over the weekend.
The SFRS said no hazardous substances have been found in their investigation.
The council said there has been no evidence of gas leaks. Tests for carbon monoxide and carbon dioxide were also carried out along with checks on the gas, water and electricity supplies.
A specialist firm has been contracted to carry out further investigations and the kitchen will remain closed while this happens.
Packed lunches will be provided to pupils until the kitchen re-opens and they will be taken in classrooms rather than the dining area.
Sheena Devlin, children and families spokeswoman for Perth and Kinross Council, said: “This has been a very difficult week for pupils and staff and I would like to thank them, and parents and carers, for the way they have responded this week.
“Following extensive testing and consultation with partners and NHS Tayside, we will re-open to pupils on Monday.
“However, we have appointed a specialist company to carry out a forensic check of the kitchen and its appliances to make sure everything is working exactly as it should so our staff, pupils and wider school community can have absolute peace of mind.”
