Several students have reported feeling ill at a primary school in Carterton after a plane flew over the school and one student saw "stuff" coming out of the aircraft.
The incident happened at approximately 1pm at South End School in the Wairarapa town. The school says all students are now "fine".
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.
A statement on the school's Facebook page reads: "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."
The statement continues: "I have made them wash their face and drink plenty of water."
In a more recent statement the school says no students are allowed out of the school grounds and no one is allowed into the grounds.
"ALL students are fine and being looked after," the statement reads.
A Wellington Free Ambulance spokesperson says they have four ambulances at the scene.