About 100 mountain rescuers, soldiers, police and workers from a nearby power plant were mobilized for the search, police spokesman Hanspeter Kruesi. The bodies of three men were found shortly before midnight at the entrance to a nearby lake, he said.
“The location where they were found suggests that the victims were swept away by rocks and a deluge of water, and died as a result,” Kruesi said. He added that the Spaniards were traveling without a guide but had previous experience with canyoning, a sport that involves jumping, sliding and rappelling into mountain rivers and swimming downstream in protective gear.
According to current information the four men — ages 30, 33, 38 and 48 — parted ways with the two women at 4 p.m. (1400 GMT) at the entrance to the gorge, Kruesi said. A heavy storm erupted directly over the gorge shortly after 6 p.m., he said. Armin Grob, a member of the Alpine rescue squad, said the deluge flooded the gorge, a popular canyoning destination located about 85 kilometers (53 miles) southeast of Zurich.
When the men didn't show up at a parking area, the women — one of whom was married to one of the men — informed police, he said. Rescuers had to break off the search overnight due to adverse weather but resumed looking for the fourth man Thursday morning.
Spanish Prime Minister Pedro Sánchez expressed his condolences to the victims’ friends and families. In a tweet, he also thanked rescue teams involved in the search. There have been numerous fatal canyoning accidents in the Alps over the years.
In 1999, a group of foreign tourists on a canyoning expedition near the Swiss resort of Interlaken were swept away by a flash flood. Eighteen young people from Australia, New Zealand, Britain and South Africa, and three of their guides drowned.
Six former employees of an adventure company the tourists had booked with were convicted of negligent manslaughter over the Saxet Brook disaster and received suspended sentences.