VIENNA (AP) — Police in Vienna launched a criminal investigation after three women were found dead in a brothel, authorities said Saturday.

A witness discovered traces of blood outside the building, located near the Danube River, and alerted police on Friday evening. The bodies of the three victims had “cuts and stab wounds,” police spokesperson Philipp Hasslinger told The Associated Press.

A 27-year-old man was soon arrested in the vicinity of the brothel while carrying a knife, the supposed weapon. Police said the suspect is an asylum-seeker from Afghanistan and will be questioned by police later on Saturday.

Police found a fourth woman inside the brothel and she was being questioned by the police as a witness.

The identities of the three victims remains unclear. Brothels are legal in Austria.