This is the terrifying moment a helicopter fighting a massive wildfire in France crashes into a lake while scooping water in front of a shocked spectator.

The dramatic incident occurred above Rosporden Lake shortly after 7pm on August 24.

A Morane 29 water bomber was in the midst of scooping water when it dropped too quickly and despite slowing, the tail ended up hitting the water, causing it to spin out of control before it then crashed into the water.

Video shows the helicopter dipping too low, and spinning before it plunges into the lake.

The aircraft had just completed a mission against a vegetation fire in Beuzec-Cap-Sizun earlier that day, completing 27 water drops and helping protect a 10-hectare area.

While a fire threatened a home near Rosporden, the helicopter was performing a refilling operation when the accident occurred.

The prefecture of Finistere confirmed that the pilot and the firefighter on board were able to exit the helicopter on their own and reach the shore unharmed.

Witnesses described how quickly the helicopter ended up in the water with one bystander, named only as David, saying it all happened in less than 10 seconds.

David said: 'The helicopter dipped way too low and was descending fast. I thought it was going to explode, break into pieces.

'Once it flipped, it went in all directions.'

Local authorities praised 'the professionalism, composure, and courage of the pilot and the onboard firefighter'.

They noted that this accident 'reminds us that every day, firefighters in Finistere, and those who work alongside them, risk their lives to save people and protect property'.

An investigation has been launched to determine the exact circumstances that caused the helicopter to strike the water and crash.

Meanwhile, the helicopter has been replaced by another aircraft to ensure the continuity of firefighting operations at the end of the summer season.