The Waikato Philips Search and Rescue helicopter. File photo: supplied/ Philips Search and Rescue Trust
Police said emergency services were called to a farm on French Pass Road, in Karapiro, about 2:30pm on Sunday.
Hato Hone St John said three patients were airlifted to Waikato Hospital.
One person was in a critical condition, another was seriously injured, and a third person had moderate injuries.
Fire and Emergency confirmed two rescue helicopters were at the scene.
Firefighters had responded to the incident, working to remove people trapped under the the ATV, and to set up a safe landing zone for the rescue helicopters.
"Enquiries into the circumstances of the crash are under way," said police.
