A father in Germany has found the bodies of six teenagers, including his own son and daughter, after a party in a shed ended in tragedy.

The five young men and a woman, all aged 18 and 19, had been having a birthday celebration outside the town of Arnstein in the southern state of Bavaria on Saturday night.

Police are reportedly examining a wood-burning stove from the shed to see if carbon monoxide poisoning could have caused the sudden deaths.

The six youths were using the heater to keep warm, so carbon monoxide poisoning "is a possibility, but there are others,” local police spokesman Bjorn Schmitt told the Bild newspaper.

The father made the grim discovery after going to look for the teenagers when they failed to emerge from the hut or answer their phones in the morning.

German media reported that the man’s daughter had been celebrating her 18th birthday.

The father called the emergency services but the teenagers were already dead.

The small town of around 8,000 is said to be in shock, with the town hall flag flying at half-mast and church services held.

The names of the teenagers have not yet been released.