The victims had not been identified pending notification of family. They were an elderly male, and elderly female and a younger male.
Authorities said the house had not been ransacked and there were no signs of a struggle.
"They appear to be the victims of foul play," Joseph Macellaro, chief of detectives for the Bergen County Prosecutor's Office, told The Record of Bergen County.
Bergen County Prosecutor John L. Molinelli said law enforcement personnel found bodies when they arrived at the Tenafly Road home around 6 p.m.
Investigators armed with flashlights then began searching areas of the home's front yard while authorities worked to get a search warrant for the residence. He added it was "definitely not a murder-suicide."
Police say the bodies of two elderly people and a man in his 20s were found with multiple stab wounds. They do not believe the incident was random.
A relative of at least one of the victims made the gruesome discovery. Investigators say all of the bodies were found on the second floor of the home.
Police say three bodies had multiple stab wounds and they were decomposing, suggesting that they had been in the home perhaps as long as a week.
The younger male victim appeared to have defensive wounds on his body.
Authorities closed down a stretch of Tenafly Road, from Benjamin Road to Tenafly Court, shortly after arriving at the home, causing traffic delays throughout the area Friday night.
They also set up two tents and a generator in front of the three-story home, which has an attached garage. Sheriff's officers and the county medical examiner were at the scene along with local police and detectives from the prosecutor's office.
Tenafly is a community of about 14,000 located about 10 miles north of midtown Manhattan.
