A 22-year-old man is accused of killing his father and 12-year-old sister at home with his younger brother, 9, witnessing it.
Michael J. Andreev Jr. has been arrested and charged with two counts of murder and a weapons charge in Sunday's killings, the Syracuse Post-Standard reported.
Trooper Jack Keller, a spokesperson for the state police, said Andreev Jr.'s young brother witnessed the stabbing attack but did not say if the boy was harmed.
Responders pronounced Michael J. Andreev Sr., 67, and Sofia Trusova, 12, dead upon their arrival to the home in Jordanville, a hamlet of Warren, which is about 20 miles southeast of Utica, New York.
Police say Andreev Jr. was found injured outside the home and was taken to a hospital for treatment. He was arrested upon his release from the hospital and is being held without bail.
An email was sent to the Herkimer County district attorney's office seeking attorney information for Andreev Jr.