Investigators believe a helicopter clipped a wire, before crashing yesterday in the Kander Valley of the Bernese Oberland.

Three professional pilots were on a training flight leaving yesterday afternoon from Belp in the canton of Bern. All three died in the crash. 

The civilian helicopter, operated by Heliswiss, crashed in rough terrain making salvage efforts difficult. 

Andreas Hofmann with Bern Cantonal Police told public television the work continues, and rescuers need to see what can be done in the area.

Federal aviation crash investigators did not want to comment further, publicly, to protect those involved in the case.