ZURICH (Reuters) - A family of four, including two children, were killed on Saturday morning after their small plane crashed in a Swiss forest, causing a forest fire that completely destroyed the plane, police said.

The plane crashed in an inaccessible area of forest in the Rengg mountain pass in the canton of Nidwalden.

“Before rescuers could make their way to the scene, a fire which spread out over the wooded area had to be put out by helicopter and a path had to be cleared to the wreck,” police said in a statement.

An investigation into the accident determined that the four victims discovered at the scene were a family -- two parents and two minor children -- from the region, who had set off in the direction of France at 9:30 a.m.

The cause of the crash is still under investigation.