The shootings happened Friday afternoon in the East River Gardens neighborhood of Newton Falls, Ohio, the Youngstown (Va.) Vindicator reported.
Police were alerted to a shooting at an East River Gardens home around noon. When police arrived at the scene, Rikki Cogley, his wife, Kathy, and her son, Everett Greathouse, 14, were found dead. A 5-year-old boy managed to escape the gunfire unharmed and run to a neighbor's house for help.
While investigating the shooting, police learned Robert Brazzon, who lived in the area, was seen fleeing in a white car, police said.
Brazzon was spotted parked in a cemetery around 4 p.m. and after a brief standoff with police, he shot and killed himself, CNN reported.
Later, a 38-year-old woman believed to be Brazzon's girlfriend was discovered shot and killed in Brazzon's home.
"We still unfortunately have three different crime scenes, a lot of different agencies are involved trying to sort through the mess, for lack of a better word," said Police Chief John Kuivila of the Newton Falls Police Department. "We are fairly confident that these homicides are related."