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."
Yosemite climber falls 30 feet, suffers major injuries
Lytro unveils camera that can focus a photo after shooting it