"The geographical isolation meant there were a few barriers."
While the mini tanker was full of diesel, Mr Gradwell said the fuel didn't catch alight as easily as petrol. "It takes a considerable amount of energy to catch fire."
Forestry contractors at the scene had managed to get the woman out of the truck before fire crews arrived.
Because they were first on the scene, Mr Gradwell said fire crews provided first aid and made sure the scene was safe while they waited for ambulance and police to arrive.
He said the driver of the truck was uninjured but shaken.
Taupo St John Ambulance transported the woman to hospital with moderate to minor injuries.
She remained in Rotorua Hospital yesterday. Police are investigating the crash.