The horrific accident occurred when a helicopter, which was on its way to a mountain-top construction site dropped a concrete-filled container on the Alpine ski-lift.

Jakob Falkner, the director of the cable car operating company said the blow knocked one car off its wires, killing three of the five passengers, and also shook the car just ahead of it, causing six of the eight occupants to fall out of the car to their deaths. And it shook the cable car just below, injuring one person, he added.

According to the Bergbahnen Soelden construction company using the helicopter, a 750-kilogram (1,650-pound) container carrying concrete for use in building a foundation fell from a height of 300 meters (1,000 feet).

Besides the nine people who were killed, a further seven were injured, and four of them are in a critical condition. Survivors were hoisted to safety by a helicopter.

Investigating the cause

The investigations, which got underway on Tuesday, are concentrated on the helicopter, which has now been seized for futher examination. Police commander Oskar Gallop said it was "too soon" to say whether the accident was due to a technical breakdown or human error, adding that a judicial commission would investigate the cause.

The head of the helicopter firm, Roy Knaus, told reporters that the pilot was "in a state of shock" and had "no explanation" for what had happened. But public prosecutors in the Austrian city of Innsbruck have opened a preliminary manslaughter enquiry.

German Transport Minister, Mandred Stolpe and his Austrian counterpart, Hubert Gorbach, are meeting in Soelden on Tuesday to talk about the tragic accident. On Monday, Gorbach described the incident as a "mixture of unfortunate circumstances."

Ill-fated skiing trip

Police are expected to begin releasing details of the victims later on Tuesday. Little is known so far, except that all those killed were German, and that six of them were children. They were heading for summer skiing on the Rettenbach glacier, at an altitude of 3,250 meters (10,000 feet), perched above the ski resort of Soelden, 60 kilometers (35 miles) southwest of Innsbruck.

More than 35 rescue workers and 12 helicopters were involved in the rescue work, Red Cross spokesman Fritz Heller said.

The cable car line, known as the Schwarze Schneidbahn, is almost two kilometers long, rising from 2,675 meters to 3,250 meters, and each car can hold eight people.

It was the worst ski lift accident in Austria since a train traveling up a mountain near Kaprun on November 11, 2000, caught fire in a tunnel, killing 155 people.