A 32-year-old man started an altercation with his neighbors in Beekman in which he stabbed three persons, killing one of them, before taking his own life, police said.

The violent incident started around 11 p.m. Wednesday, when deputies responded to a disturbance and found that Willem C. Salcius had stabbed three persons multiple times at 174 Walnut Drive in Beekman, and then committed suicide, according to the Dutchess County Sheriff’s Office.

William E. McGoorty, 35, died at the scene, while Robert M. McGoorty, 30, and Edward M. McGoorty, 58, were taken to the Mid-Hudson Regional Hospital with life-threatening injuries, police said.

The suspect knew the victims.

Police are still investigating a motive. The investigation is being conducted by the sheriff’s Detective Bureau.

Assisting the sheriff’s office at the scene were the Dutchess County Medical Examiner, Putnam County Sheriff’s Office, New York State Police, Beekman Fire Department, Pawling Fire Department, Union Vale Fire Department, Town of Dover EMS and EMStar.