Six employees of aircraft maker Eurocopter were killed when their helicopter crashed in a mountainous region of southeast France on Wednesday during a test flight, police and company officials said.

The crash occurred around 1:30 p.m. (1130 GMT) in a steep section of the Verdon Gorge in the Alpes-de-Haute-Provence region near the border with Italy, according to local police.

Police said a preliminary investigation suggested the helicopter may have hit an electric cable.

Eurocopter, a unit of European aerospace group EADS , said in a statement that the downed aircraft was a Cougar AS532 AL helicopter and that six people were on board.

It had taken off shortly before the crash from a heliport near the Mediterranean port city of Marseille for a test flight before delivery to a client.

The six people on board were company employees and included test engineers, a Eurocopter spokeswoman said.

Police said search teams were at the site investigating the cause of the crash.

“The accident occurred in a place that’s very difficult to access, which is complicating our work,” Benoit Gounine, a regional police lieutenant, told Reuters.