Police didn't release further details on the identities of the three.
The German daily Merkur reports that they had several arrows in their bodies: two had penetrated the man's head.
They were met with a weird and horrifying scene - a 54-year-old man and two women, aged 30 and 33, dead with crossbow bolts through their mid-sections and two crossbows lying on the floor.
According to local media two crossbows were found in the room by police when officers searched the scene in the remote riverside hotel near the Austrian border. All three bodies had bolts inside them but police did not say how many.
PHOTO:A guesthouse is pictured at the river "Ilz" in Passau, Germany, May 13, 2019.
The other woman was lying on the floor with a bolt in her chest. The 53-year-old was lying on a bed hand in hand with the 33-year-old, while the 30-year-old was discovered on the floor.
Police are struggling to piece together what links the five dead people as the investigation has broadened from the banks of the Danube to a mountain range over the Rhine and the rolling farmland of the north.More news: Thousands march in London for a ‘free Palestine’
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The investigators are trying to learn more about the connection between the three victims, examining evidence found in the room and a vehicle parked at the resort with stickers and plaques indicating that it could have belonged to an archer or hunter.
Police were also inspecting a pick-up truck on Monday, reportedly belonging to one of the deceased, which had an archery logo stuck on it.
The innkeeper told the paper that they hadn't booked breakfast but they had planned to stay for three nights.
"It was a odd group", a guest recalled, according to the newspaper Bild.
The first results of an autopsy are expected on Tuesday.
Prosecutors have ordered a post-mortem, police said Sunday.
Crossbows can be purchased legally in Germany by anyone over 18.