Police say the case involving two people who were found dead at an apartment building Friday in Sunset Park is now being investigated as a homicide.

The NYPD identified the two victims as 61-year-old Delma Mateo and 52-year-old Felix Santiago. Police add they were called after neighbors heard fighting and commotion inside an apartment on the fourth floor at 5320 6th Ave.

Officers found Mateo unconscious in the hallway with multiple stab wounds and cuts to her head, neck and upper torso.

Santiago was found lying on the ground at the back of the building with a knife close to him. Police say they believe Santiago took his own life.

The NYPD believes Mateo and Santiago were a couple, but Santiago didn't live in the apartment.