UPDATED: 11.11am. The woman passenger trapped in a tourist bus that crashed down a six-metre bank in Tongariro Forest Park on Sunday morning has been freed.

A police spokeswoman is unsure of her condition, except that she was partially submerged in the stream the bus landed in. The nationality of the passengers is unknown.

St John is reporting two patients suffered serious injuries and eight had minor to moderate injuries. The eight will be transported by road ambulances to Taupo. Other patients are still being assessed at the scene.

In an update at 11.56am Police say the bus was carrying a driver and 14 passengers from the United States and Great Britain, when it crashed at teh intersection of SH47 and SH48.

The passengers are beleived to be aged in their 60s.

The tourist bus was left partially submerged after crashing 10 metres down a bank and into a creek.

It was raining and there were thick heavy clouds at the time of the crash. Two passengers have serious injuries and were taken to Taupo Hospital by helicopter.

Seven others with less serious injuries were taken by bus to the same hospital.

The cause of the crash will be investigated.

Earlier:

A person is trapped in a 20-seater tourist bus that crashed six metres down a bank into water in Tongariro Forest Park this morning.

At least 15 people have various injuries, ranging from minor to moderate, and all but one are out of the bus.

One person is still trapped, partially submerged, and emergency services are working to free the individual, says a police spokesperson.

That person is breathing and conscious. The crash is reported to have occurred on SH47 and SH48 in the Ruapehu District. Thick fog in the area is delaying a rescue helicopter from getting to the scene.

Police and Fire are working with SAR to carry the injured out and up onto the road to waiting ambulances.

A St John Ambulance spokeswoman says there are three ambulances in attendance with two more on the way.

Three rescue helicopters are staging at the corner of State Highways 46 and 47, but because of the poor weather conditions it is unsure if they can reach the scene at the corner of State Highways 47 and 48.

The intersection is 7 kilometres east of National Park Village. SH48 leads to Whakapapa Village and Mt Ruapehu.