Investigators in Austria are trying to establish how a helicopter accidentally dropped a concrete block on a cable car, killing nine German tourists.
Some victims were catapulted out of swinging gondolas
It is not yet clear whether a technical fault or human error was to blame.
Six children were among the nine German skiers killed in Monday's accident in Soelden, a ski resort in the Tirol.
The block, which was to be used for construction, hit one gondola, sending it plunging down. Two other gondolas swung violently, hurling people out.
Seven people sustained severe injuries, and two of them are in a critical condition, German media report.
Pilot in shock
The head of the Soelden cable cars, Jakob Falkner, said the helicopter flight above a moving cable car had been authorised.
The block was being carried to a mountaintop site where workmen were building a telecommunications installation.
The cable car company said a 750kg (1,650lb) block fell from a height of 300m (1,000ft).
The helicopter pilot was reported to be too shocked by the incident to give a statement.
The cable cars take visitors up to the glaciers on the peaks above the village for excursions or summer skiing.
The cable car line is about 2km (1.5 miles) long, with a 650m (2,133ft) vertical ascent. Each car holds up to eight people.
The stricken route climbs to the 3,309m (10,857ft) Schwarze Schneid peak in the Oetztal area.
Last November, a cable got entangled with an empty gondola on the Soelden cable car system and 113 tourists had to be rescued from gondolas in severe frost, the German news website Der Spiegel reports.
Austria's worst winter resort tragedy in recent years was the November 2000 Kaprun ski train fire, which killed 155 skiers and snowboarders.