German police investigating the deaths of three people shot with crossbow arrows in a Bavarian hotel have found the bodies of two more women in a flat 650 kilometres away.

The latest bodies were found inside the apartment of one of the original three victims, whose bodies were found by hotel staff on Sunday.

The flat in Wittingen, in Lower Saxony, had been occupied by a 30-year-old woman who was found dead on the floor of the hotel room in Passau.

The other two in the hotel room were a man and woman aged 53 and 33 respectively. They were from the western German state of Rhineland-Palatinate.

Police say there were no signs of fights, or of the involvement of anyone else in the bizarre deaths.

They have not said how the two women in the Wittingen apartment died, or whether they have been identified. However, German newspaper Merkur reports one was the sister of the 30-year-old woman who died in Passau. The newspaper identified her only as “C” and said she had registered as an occupant of the flat in March.

The apartment is 650 kilometres away from the Bavarian hotel. Photo: AAP

Public prosecutor Walter Feiler told a news conference the dead couple on the hotel bed were holding hands and had multiple crossbow bolts shot into them.

The third victim, the younger woman, “was lying in front of the double bed and had one shot from a crossbow between the throat and the chin”, he said.

Police found the two bodies in Wittingen on Monday, as they were investigating the Passau deaths. Mr Feiler said it was not yet clear how long the bodies had been in the flat.

“The corpses were found because one of the neighbours heard about the reports from Passau and told police that the letter box of the flat was overflowing and that a strange smell was coming from the flat,” he said.

The relationship between the three victims in the hotel also remains unclear. They had booked a triple room for three nights, checking in on Friday.

The hotel in Bavaria where the first bodies were found. Photo: AAP

The BBC reports that another hotel guest, who was staying in the hotel for a short break, told local newspaper Passauer Neue Presse that it had been a “completely quiet night”.

Police have also apparently seized a white truck, parked outside the Passau hotel, which has stickers reportedly linked to a hunting club. It was registered in Westerwald, in Rhineland-Palatinate.

German media reports that one sticker has the letters FMJ – believed to be a reference to Full Metal Jacket crossbow arrows made by a US firm, Easton Hunting.

Autopsies have been ordered, with the first results expected on Tuesday (local time).

-with agencies