MURFREESBORO, Tenn. -- A 56-year-old man was killed with a shotgun by his son-in-law early Wednesday morning, police said.

The incident happened just after midnight inside a home on Maple Street near downtown Murfreesboro.

At about midnight, the victim's son-in-law said he heard a noise and got his gun to check out the situation. That's when he spotted his father-in-law, Dana Jankovoski, inside the apartment and said he mistook him as an intruder.

Jankovoski was flown to Vanderbilt Medical Center in Nashville, where he died in surgery.

Police said the son-in-law spoke with investigators and was released.

It is unclear what led to the shooting. Investigators said they have not ruled out self-defense or an accidental shooting, but it is classified as a domestic-related homicide.

The son-in-law's name has not been released, but police said they don't anticipate filing charges.