Another Israeli air force spokesman, Brigadier General Avi Benayahu said: "It would have been very difficult to have come out of this incident alive.
He said the helicopter hit the mountaintop, rolled downwards and then burst into flames.
The CH-53 helicopter was on an aviation training exercise training when it ran into poor weather conditions, although this has not been confirmed as the cause of the crash.
A list of the missing crew members has been released. They range in age from 24 to 48.
The Romanian and Israeli air forces have launched a combined investigation into the disaster.