All seven people aboard a helicopter carrying tourists that crashed Saturday on a scenic New Zealand glacier are believed to have been killed, police said.

The wreckage of the helicopter was located inside a crevasse on Fox Glacier, but difficult terrain made it difficult for rescuers to reach it, police said in a statement. They said the pilot and six passengers are believed dead.

The helicopter crashed at about 11 a.m. on the popular tourist destination on New Zealand's South Island. Police said they were attempting to notify relatives before releasing the identities or nationalities of the victims. They said they would try again to recover the bodies Sunday.

Grey District Mayor Tony Kokshoorn said the weather was marginal at the time of the crash, with intermittent rain showers and low cloud.

"It was not ideal for helicopter flying," he said.

Kokshoorn said the region had been experiencing a bumper start to the Southern Hemisphere tourist season, but that bad weather had been putting pressure on some tourist operators.

"It can be a fine line," he said. "Operators are doing their best to get people up there, but obviously something went badly wrong."

He said the glaciers in recent years have been retreating and the only way to view them up close is by helicopter. He said operators offer different packages, and a basic trip typically involves a 10-minute flight to the top of the glacier, where tourists can walk about for about a half hour before returning.

Rescue teams reached the scene Saturday afternoon, however, crevasses and rugged terrain were hampering their efforts.

A rescue helicopter used a winch to lower a paramedic and an alpine rescue team to the vicinity of the crash, said Vince Cholewa, a spokesman for Maritime New Zealand. He said the area where the helicopter crashed was filled with treacherous terrain.

He said there was low cloud in the area, but otherwise the rescuers had not been hampered by the weather.

Peter Northcote, a spokesman for the Transport Accident Investigation Commission, said the helicopter was ferrying tourists at the time. He said a team of investigators was planning to survey the scene.

Nine people died in 2010 when a skydiving plane crashed near the same glacier.

New Zealand relies on tourism as a major source of revenue, but has been criticized by some people as having safety standards that are too lax. The parents of four tourists who died in the 2010 crash near Fox Glacier later wrote to New Zealand Prime Minister John Key urging him to improve safety measures in the industry.

Kokshoorn, the mayor, said he hopes authorities complete a thorough investigation into the latest crash to ensure the industry is safe and that tourists can have confidence that operators will make the right call in bad conditions.