The police found five dead in a residential building in Königs Wusterhausen south of Berlin.
A call was received a few minutes before noon, a spokesman for the South Police Department said on Saturday.
The caller found it unusual that the residents of the house could not be seen.
"We assume that it is a homicide crime," said the spokesman.
The homicide squad is investigating.
The press sovereignty lies with the Cottbus public prosecutor.
The authority could not be reached at first.
In the afternoon, officials from forensics were still on site.
The road was blocked, said the spokesman.
The police were initially unable to provide any further information.
Initially, several media reported.