A nest of wasps disturbed at a Nelson beach stung a group of school pupils, with nine taken to hospital, and put a grandmother in a serious condition.
About 90 Victory Primary School pupils were on a treasure hunt at Tahunanui Beach when one disturbed a wasps' nest about 12.30pm.
Nine children, all aged about 10, were taken to Nelson Hospital after being stung multiple times, St John Ambulance operations team leader Matt Wilkinson said.
One woman, a grandmother of one of the students, went to hospital in a serious condition after suffering an allergic reaction.
One pupil, Jovaan Lenoel, 8, said one of his classmates stood on something and "heaps of wasps came flying from the ground".
"There was this girl who was trying to find treasure and then a bee stung her on her neck."
Everyone was screaming and running, he said.
Jovaan said he could not really see anything because "too much was going on".
He was stung eight times around his body, arms and legs.
"They managed to get inside my T-shirt. I have no idea how that happened."
Jovaan was really scared and had never had anything like that happen to him before.
Jovaan's grandfather, George Smith, said the wasps were "everywhere".
"Our first reaction was just grab the kids and run away."
He was stung five times.
"It did not matter, I was just trying to do what I could to get the children safe. It was madness," Smith said.
Nelson City Council communications manager Angela Ricker said Nelmac's wasp eradication expert was now at the site.
They had cordoned off the area, near the beach cafe, and were in the process of poisoning the nest.
Councillor Matt Lawrey, who was a parent helper for the trip and the first person to inform the council of the drama, said he had been impressed to see parents, kids, teachers and emergency services working together.
It must have been frightening for the children and yet they all handled it very well, he said.
"You could see people hightailing it away from the wasps and regroup," Lawrey said.
"Everyone banded together and it was remarkable."
It was a great lesson for the children on how to build resilience.
"Kids will be talking about this for years and years. It has been more than a beach trip, it has been an adventure."
Dave Sullivan, deputy principal of Victory Primary School and the teacher in charge, said the pupils had been searching for the last clue in the treasure hunt when the wasps' nest was disturbed.