MADISON, Maine (AP) — Maine state police say they don't know what drove a man to kill three people and wound another before being fatally shot in a confrontation with officers.

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Spokesman Steve McCausland says detectives are trying to determine what sparked the violence Wednesday morning in the town of Madison.

The spokesman says 51-year-old gunman Carroll Tuttle killed his partner, 52-year-old Lori Hayden, and their son, 25-year-old Dustin Tuttle, at their home. The third victim was 57-year-old Michael Spaulding, who was killed at a nearby residence.

McCausland says the gunman returned to the original location and wounded a fourth person before being shot and killed in a confrontation with deputies.

It was the deadliest shooting in Maine since November 2015, when a gunman killed three people before taking his own life in Oakland.