A sudden change in the wind is being blamed for cannabis smoke wafting across the grounds of a Picton primary school.
St Joseph's School principal Peter Knowles noticed smoke coming from the Picton police station on Friday morning while the children were in class.
He and a member of the school board went to the station about 200 metres away and police put the fire out immediately, he said.
The incident was "very unusual and out of the blue" and he did not know whether the smoke smelled of cannabis, he said.
Senior Sergeant Peter Payne, of Picton, said shredded paper and a small amount of cannabis were being burned in the incinerator at the station when the direction of the wind changed unexpectedly.
When the fire was lit the smoke was blowing in a direction where there were no houses or people; the amount of paper burned was significantly more than the amount of cannabis, he said.
A concerned parent who called The Marlborough Express had never heard of police burning cannabis and was worried about children at the school.
Sergeant Payne said the incinerator at the station was quite small and large amounts of cannabis were usually burned in a commercial furnace.
"A big gust just came and took it [the smoke] in a different direction. It can't be helped, it's just an act of nature," he said.
- The Marlborough Express