Emergency services were called to the Omarama Top 10 Holiday Park about 1.20pm on Monday.
Holiday park owner Erwin Beiboer said he had not seen anything like it before.
The small town in the Waitaki District near the southern end of the Mackenzie Basin is a popular holiday spot for Cantabrians over summer.
The campground was booked out with holidaymakers today.
The tornado lasted for a few seconds in an area with caravans and tents, he said.
"There were people in the tents and were lifted up a few metres, luckily the tent was open so they could actually fall out [and] jump out," Mr Beiboer said.
"The tent went up a few hundred metres . . . over our trees into the neighbour's paddock."
Emergency services remained at the scene checking over "mainly frightened" people over, he said.
A Hato Hone St John spokeswoman said one ambulance had been sent to the incident and initial indications were of minor injuries.
"Four patients were assessed and treated at the scene, all in minor conditions, no transport required," she said.
A Fire and Emergency spokeswoman said two fire appliances had been sent to assist ambulance staff.
