The 50-seater, four-engine Dash 7 airplane, crashed into a field at Owlescombe Cross, near Bickington, Devon, at about 0945 on Saturday.

The airplane, which did not have passengers on board, took off from Guernsey at 0917 for a 90-minute test flight which was due to finish back on the Channel Island.

Devon and Cornwall police received more than 20 calls from residents and motorists on the nearby A38 as the airplane lost height and disappeared before a cloud of smoke billowed from the crash site on the edge of Dartmoor.

Rescuers were hampered by the terrain and fire engines had to be towed across the field by tractors.

Local farmer Roger Parker, 56, watched as the airplane flew over his property.

He said: "The plane faltered a bit and the pilot turned to the right. When it crashed there was a horrendous explosion and a mushroom cloud of smoke rose from the area.

"The pilot must have turned the plane to avoid the edge of the town and the main A38.

"If he hadn't of done that it could have been awful.

"He must have known there was something wrong and turned the plane towards the moors where there were no houses.

"He was a brave bloke."

Philip Poole, from Ashburton, was walking through the town when the airplane flew overhead.

He said: "It was a large white aircraft and it caught my eye. I watched it fly over at about 400 to 500ft.

"It was making a different noise to what they normally do and after I had stopped looking at it I heard a substantial thud.

"Once I saw the emergency services I knew it must have crashed."

Police are trying to establish the owner of the plane and contact the families of the men involved.