Swiss police say two people are dead after a canyoneering group was caught out by a sudden flood in an Alpine stream.

Police in the northeastern canton (state) of St. Gallen say rescue services were able to evacuate five members of the group after the water level in the Fallenbach stream rose suddenly and unexpectedly on Sunday afternoon. Three were taken to a hospital with light injuries.

But they said Monday that the bodies of the group's 24-year-old Belgian guide and a 23-year-old German woman were found several hours later.

Canyoneering involves jumping, sliding and rappelling into rivers and swimming downstream without a raft.

In 1999, 18 tourists and three guides drowned when they were swept away by a muddy wall of water in a brook in central Switzerland.