LONDON, Nov. 17 -- Four people were killed on Friday in a mid-air collision between a helicopter and a light aircraft in Britain.

Four killed in helicopter, light plane mid-air collision in Britain.[Photo/Xinhua]

Local police said two people were killed in each aircraft, but haven't given any details of the identity or the genders of the victims.

Police and the Air Accidents Investigation Branch (AAIB) said they have launched a joint investigation to establish the cause of the collision.

Wreckage from both aircraft was discovered near the estate grounds of historic Waddesdon Manor near Winchendon, Buckinghamshire.

Witnesses said they heard a loud bang over woodland shortly after midday before realizing there was a mid-air collision. Both aircraft involved, which were flying at low altitude, had taken off from Wycombe Air Park, about 25 km to the southeast of the estate.