Two jockeys were thrown from their mounts at Tauranga races, leaving one with suspected spinal injuries.
The falls occurred during race four of yesterday's annual Interislander Summer Festival Tauranga Races.
Apprentice jockey Jenny Whiteside, from Auckland, was riding Te Awamutu-owned and trained horse Roydon, when he fell about 450m from the finish of the 2100m race.
Ms Whiteside was treated at the scene by a course doctor and attending St John staff before being taken to Tauranga Hospital for further treatment and x-rays.
The incident left her concussed and complaining of back pain.
Ms Whiteside's mount, Roydon, was put down at the track.
Stipendiary stewards panel chairman John Oatham said: "Jenny was knocked unconscious from the fall and when she came around she was a bit confused and concussed, but was conscious and talking when she was taken by ambulance to Tauranga Hospital.
"I can't confirm the exact reason for the fall at this stage, not until we have spoken to Jenny, but what I can say is that her mount, Roydon, fell and when the horse was examined by the course veterinarian it was found to have a fractured shoulder. It's not clear whether the injury occurred before the horse fell, or was a result of the fall."
A Tauranga Hospital spokesperson said last night that Ms Whiteside had been admitted to a ward in a stable condition.
The Bay of Plenty Times understands she was being treated for suspected spinal injuries.
Two other jockeys, also involved in the accident, both sustained bruising after being thrown from their mounts, forcing one to retire from racing early.
Mr Oatham said Bon Genie - the horse following Roydon - fell over top of it, dislodging jockey Vinnie Colgan.
"Mr Colgan was a bit bruised and after being examined and cleared by the course doctor he was able to carry on riding for a while but later retired after feeling too unwell," he said.
Mr Oatham said the third horse involved, Straight Furrow, did not fall but its jockey, Craig Grylls, fell off.
Mr Grylls also suffered bruising but carried on and rode the winners in the final two races.
Mr Oatham said he could not comment further on the accident until his inquiries were complete.
He said falls in races did happen from time to time and was hopeful Ms Whiteside would make a full recovery.
"Luckily the rest of the day's racing was relatively incident-free," he said.
The accident comes closely on the heels of the death of Gold Coast-based jockey Ashlee Mundy, 26, who fell from her horse at the Kurow races in North Otago. The former Cantabrian had returned to New Zealand from Queensland in mid-December to ride the South Island's summer circuit.
Her mount, Elleaye, fell with 600m to run in the seventh race.
Miss Mundy landed on her head, receiving non-survivable injuries, and it is understood she may have been trodden on by another horse.