The aircraft came down at around 13:40 local time in the Verdon Gorge, an area popular with hikers.
The helicopter, reportedly a Cougar, belonged to aviation company Eurocopter and was on a test flight involving pilots and engineers, officials say.
Witnesses said the helicopter had hit an electricity cable before plunging down onto the river bank.
Firefighters and a team of climbers were dispatched to the scene, as well as a medically-equipped helicopter.
The helicopter came down in one of Europe’s best known river gorges, which runs 700 m (2,300 ft) deep.
Police spokesman Benoit Gounine told reporters that rescuers had trouble reaching the site.
“The accident happened in a very difficult place to access, which complicates our work,” he said.
Investigations are taking place to determine the cause of the crash.
Quincy Jones, the celebrated musician and producer who worked with Michael Jackson, Frank Sinatra, Ray…
Misleading allegations, rumours and outright lies about voting and fraud are flooding online spaces in…
At least 158 people have died in Spain's worst flooding disaster in generations. On October…
Google has been fined two undecillion (a two followed by 36 zeroes) roubles by a…
Embarking on a home remodel is an exciting journey, promising enhanced comfort, increased property value,…
The US presidential candidates continued to campaign across key swing states on October 20. Footage…