Ten primary school children in Carterton have been taken to Wairarapa Hospital after a plane is thought to have accidentally sprayed the school with pesticide.
The incident happened at approximately 1pm at South End School in the town.
Wellington Free Ambulance says 10 children with moderate symptoms have been transported to the hospital in Masterton and paramedics are treating 40 other people - children and adults - with very minor symptoms.
Four ambulances and a Lifeflight helicopter are being used, Geoff Procter of Wellington Free Ambulance said.
“We are taking a precautionary approach. All the children and their families are being well looked after with extra food and water," he said.
One-hundred-and-seven people are going through a decontamination process, consisting of washing down, and fresh dry clothes, Mr Procter said.
"The decontamination process takes a while. We’re all here and on hand to make sure everyone is safe and well.”
Symptoms the affected children have are generally low-level, consisting of nausea, vomiting and itchy eyes, he said.
Mr Procter advises that if anyone‘s condition deteriorates, call 111.
Parents have been seen arriving at the school with a change of clothes and children are slowly coming out one by one in towels.
Carterton Fire senior station officer Wayne Robinson said local people have been presenting to the local medical centre after the incident.
A 1 NEWS reporter at the scene says there are numerous appliances there and roads are blocked in several directions.
NZ First MP Ron Mark who lives in Carterton has told 1 NEWS it seems a plane has accidentally sprayed the school with pesticide.
Police say they are investigating and are going door to door in the area checking on residents' welfare and trying to locate the source of the smell.
They are also searching the school's grounds.
Carterton District Mayor John Booth says parents are very worried.
A statement on the school's Facebook page read: "A plane flew in a southward direction and one student had seen 'stuff' coming out of the plane - so we assume it was a fertiliser of some sort - several students have experienced feeling quezzy and ucky."