When police and fire officials broke into the garage of an Ohio family on Monday afternoon, they found a horrifying sight: two adults and three children, all dead from carbon monoxide poisoning. Officials believe it wasn’t an accident.

The story is still being pieced together, but police think a custody battle is at the center of the deaths. The adults, 56-year old Sandy Ford and her son, 32-year old Andy, were not the parents of the children. She was their grandmother; her son, their uncle. Neighbors say the children often spent time at the house but did not live there full-time. Police were called to the home after Sandy’s husband, Randy, found suspicious notes in the house from his wife, son, and the children. When he couldn’t get into the garage, he called 911. Officials are treating it as a murder-suicide under suspicion that Sandy was upset that her daughter, Mandy, was about to regain custody of the children.

One neighbor says he saw a police car parked at the house a few days ago but never found out why an officer was there. The deaths have come as a shock to the neighborhood, especially to those who just recently saw the family doing yardwork together.

“One minute they’re doing the leaves, and then the next there are cop cars all over,” neighbor Eric Pieper said.