Search and Rescue and St John Ambulance staff have all been called to the scene to assist with the rescue.
It is expected to be long and difficult operation and Mr Van Kalken said it was likely to take as long as six hours to get the woman out.
"A rescue helicopter is currently on standby to airlift the injured woman to hospital once she has been brought to the surface."
Mr Van Kalken said the woman fell about 8m.
The rescue team has taken a stretcher and a paramedic to give the woman pain relief.
Luckie Strike - off Waipuna Rd, about 20 minutes drive west of the village of Waitomo Caves - has a reputation among cavers as one of the most physically demanding and beautiful caves in the country. It is near Ngapenga, 32km west of Te Kuiti.
The woman is lying about one hour's travel into the cave, which requires traversing, climbing, crawling, abseiling and squeezing through wet and dry passages and up waterfalls.
"She is about an hour from the surface - which could translate into five hours back to the surface," said a spokesman for the rescue coordinators.
Further rescue crews were being organised to go in and help with carrying the stretcher.
"It's a moderate scramble for a cave - it's not very easy to walk through," the spokesman said.
"It's going to be pullies and ropes and hard work until midnight."
Last year, Motueka doctor Michael Brewer found himself in a similar situation - injured and trapped 400m underground in the Middle Earth cave under Takaka Hill near Nelson.
It took nearly three days and a highly complicated rescue effort involving about 50 cavers to extract him.
- NZPA
