The Serious Crash Unit attended, she said.
A Te Whatu Ora- Capital and Coast spokesperson said the person remained in a critical condition in ICU on Tuesday afternoon.
Waimarama resident and new regional councillor Sophie Siers said the community had been hit hard by the news.
"These things really impact on small communities. It is so personal when something happens in your backyard so to speak," Siers said.
"I'm really feeling for the community and for the families of course."
Waimarama resident and Ngāti Kahungunu Iwi Chairman Bayden Barber said the news had taken him and everyone by surprise.
Police were working to speak with a number of people who were at the scene, as part of an ongoing investigation into what happened.