Such a total was unusual, but possible given the size of the crowd, St John district operations manager Ian May said.
"Part of good organisation is to cater for both the crowd and the participants of the event, as occurred on this day."
Organiser Julia Murray said there were also two crashes during the night's events, which left two people bruised.
There had never been previous medical incidents.
"We've had no issues with the crowd needing an ambulance, though there was one asthma attack. We've never had two in one night."
St John staff had to be there during races. On Saturday the races were able to continue because another staff member was present.
"It was an exciting night - the racing was exceptional," Mrs Murray said.
St John staff were in action again on Sunday, when a 4x4 truck rolled in the fourth event of the Suzuki Extreme 4x4 Challenge at Turakina.
The 45-year-old Kapiti Coast driver, Warren Jeffery, had to be cut free of the truck's roll bars.
He suffered serious spinal and abdominal injuries, Mr May said, and was treated at the scene and taken to Whanganui Hospital. He was still there yesterday, in a satisfactory condition.
Event organiser Dan Cowper visited Mr Jeffery, and said he was not paralysed and with time would be all right.
Motor sport was safe, he said.
"It's not nice to see anyone get an injury. I've been in this sport all my life and I've seen a lot worse accidents than that. There's danger of course, but it was an unlucky landing or a bounce, coming down hard on the roof. It's just bad luck."
