At least 18 people were killed in a "canyoning" accident in a gorge near the tourist resort of Interlaken in central Switzerland yesterday, police said.
The accident happened in a gorge on the small Saxeten river near the village of Boenigen, some 37 miles south-east of the Swiss capital, Bern.
"I can confirm that 18 people were killed and there are six others injured," Berne police spokesman Mr Peter Abelin told Reuters.
He said it was not a rafting accident as had initially been assumed. No further details were immediately available as to the exact number of dead or their nationalities.
Canyoning, a dangerous sport popular with tourists visiting Switzerland's alpine resorts, can involve navigating a river or waterfalls equipped merely with wetsuits, helmets and secured at times by mountaineering ropes.
Swiss television reported that up to 17 people might have drowned in the accident, when the victims were apparently surprised by heavy rain and got caught when waters suddenly swelled and swept them away.
A spokesman for Swiss helicopter rescue service, Rega, told Reuters that according to reports he had heard, the number of dead might be as high as 20.
"Everything is in flux. I can only tell you that as far as Rega is concerned, we got an alarm at 5.47 p.m. [local time]. We have deployed four helicopters," said Rega spokesman Mr Thomas Kenner.
An official of Adventure World, the company organising the canyoning excursion, told Reuters investigations were still going on. She said she also could provide no further details.