Eight members of the same family are dead and police say remaining relatives could be next.

Eight people were killed in four separate attacks in an American town on Friday. The killings could have been seen as random, except all eight victims are members of the same family.

Now police in Piketon, Ohio, have warned the surviving members of the Rhoden family that they “could be next” as they try to piece together what happened.

You can watch the CNN news report below. Post continues after video.

The Ohio Attorney General Mike DeWine has called the killings a “pre-planned execution” after all eight members, aged between 16 and 44, were found murdered execution-style, each with a bullet to the head.

“This is not your case where someone got mad at somebody else, they shot them, there’s a witness, two witnesses,” he said. “It is a very, very, very different type case.”

The massacre saw several of the family members shot while they were asleep. The motive for the killings is still unknown. However, reports emerged today that marijuana growing operations were found at three of the scenes, yet it is unclear if this played a part in the killings.

According to American news site News24, officials said on Sunday the killings were part of "a sophisticated operation".

The killers are said to have spared the life of three children found at the massacre sites, a four-day-old baby found lying next to their dead mother, a six-month-old infant and a three-year-old.

Pike County Sheriff Charles Reader said other family members have now been warned, "I cautioned them they are a target and I cautioned them to be armed." He also said other members of the community should not feel threatened.