Varone, who was asked repeatedly by reporters Thursday about the DVD theory, declined to address questions directly. But he said that no line of inquiry was being excluded or made a priority.
In Sierre, locals expressed their shock at the tragedy.
"I am very sad, because I have children and today I awoke with them and I think very strongly about these people because it's really very hard," said Genevieve Romailler, a pharmacist.
"It's very hard to come to terms with this kind of situation. Even if we didn't know these young victims, we are really taking this to heart and we really moved by this tragedy," said barman Franck Bartolucci.
A Catholic chapel in Sierre was opened to allow the public to pay their respects to the victims, and a memorial mass was planned for Thursday evening at the town's Holy Cross church.
The Vatican conveyed its condolences to Belgium's Archbishop Andre-Mutien Leonard.
Pope Benedict XVI was praying for the mourning families and had conferred a special blessing on all affected, the Vatican statement said, and he wished to express his "profound sympathy" to the injured and their families and his sense of "closeness" to the rescue workers.
Hundreds of locals, young and old, packed the Holy Cross Church in Sierre for a memorial Mass held by Bishop Norbert Brunner of the Roman Catholic Diocese of Sion. The church fell silent Thursday night as the bishop presided over prayers for the dead and invoked the Catholic creed that they would be resurrected.
At the entrance, on top of a basin meant to hold holy water, was a child's drawing depicting hearts and candles.
Jeffrey Schaeffer in Sierre, Switzerland, Nicolas Garriga in Sion, Switzerland, Don Melvin and Raf Casert in Brussels, John Heilprin in Geneva and Victor L. Simpson in Rome contributed to this report.
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