UPDATED 9.40PM: Police believe the six passengers who died on the Fox Glacier today were from overseas.

They say two were Australians and four were from the United Kingdom.

The pilot is also assumed dead after the Squirrel helicopter crashed around 11 this morning.

Rescue crews have found the wreckage - wedged into a crevasse on the glacier.

Spokesperson for the Transport Accident and Investigation Commission Peter Northcote said investigators hope the weather will clear enough to enable rescuers to reach the scene tomorrow morning.

Mr Northcote said the first priority is the safety of the team sent to investigate.

 "Our understanding is there is some weather difficulty with the site this late afternoon and evening, so that detail will be worked through once we get into Fox and work in with the police and other authorities."

Investigators, who are working with police and alpine search and rescue, are hoping to make it to the scene tomorrow morning.

A pilot and six passengers were on board, when the helicopter went down at around 11 this morning.

Police are leading a recovery operation and scene examination, but this is likely to take some days.

The next of kin are now being contacted by police.

Fox and Franz Josef Heliservices is operated by Alpine Adventures.

Emergency services were alerted to the incident just before 11am this morning, including four rescue helicopters and an ambulance. 

The region is a popular destination, with tens of thousands of tourists converging there every year to visit one of New Zealand's natural wonders.

Five years ago, nine people died when a plane full of skydivers crashed not long after take-off at Fox Glacier.

A review into the investigation released last month by the Transport Accident Investigation Commission found the cause of the disaster may never be known.

In 2008, three people survived a plane crash at Fox Glacier.

A Cessna went down trying to land at the airstrip leaving the pilot trapped briefly.

Two passengers managed to get out of the wreckage.