The murders of eight family members in rural Ohio were sophisticated, planned executions, authorities have said.
It also emerged that several marijuana-growing operations were found at the crime scenes but investigators said it was unclear what, if any, role it had in Friday's massacre at four homes near Piketon.
Marijuana, both recreational and medicinal, is illegal in the state.
Residents have been told they are safe, but to arm themselves if they are fearful.
The killings were "a sophisticated operation", attorney general Mike DeWine said at a news conference in the small community that has been on edge since seven adults and one teenage boy were found shot in the head.
Authorities remained tight-lipped about details of the investigation, any suspects or motives for the crime.
Pike County sheriff Charles Reader said that in his 20 years in law enforcement, he never interacted with the Rhoden family "in a criminal nature". He said it was clear the family was targeted however, and he had told the victims' relatives to arm themselves.
Sheriff Reader said he did not believe safety was an issue for others, but added: "If you are fearful, arm yourself."
Authorities have been scrambling to determine who targeted the clan and why. Investigators have interviewed 50 to 60 people in the hope of finding leads and a 38-strong team is combing wooded areas around the shooting scenes to ensure no evidence has been missed.
Mr DeWine said the state's crime lab was looking at 18 pieces of evidence from a DNA and forensic standpoint and five search warrants have been executed. Post-mortem examinations were expected to be completed on Monday.
"This was very methodical. This was well planned. This was not something that just happened," said Sheriff Reader, noting most victims were targeted while they were sleeping.
The victims were identified as 40-year-old Christopher Rhoden; his 16-year-old son, Christopher; 44-year-old Kenneth Rhoden; 38-year-old Gary Rhoden; 37-year-old Dana Rhoden; 20-year-old Clarence "Frankie" Rhoden; 20-year-old Hannah Gilley; and Hanna Rhoden, 19.
Hanna Rhoden was in bed with her newborn baby nearby, authorities said. The infant was four or five days old. The newborn, Hannah Gilley's six-month-old baby, and another small child were unhurt.
Since the murders, authorities have refused to discuss many details of the crime, a potential motive, weapons, or the search for the assailant or assailants.
"We don't know whether it was one or more people involved in this," Mr DeWine said.
Maggie Owens, 39, a cook at the town's Riverside Restaurant, said: "I know a lot of people are just scared. You don't hear about stuff like that around here."
She said her son was friends with the younger Christopher Rhoden. She described Dana Rhoden as a woman with "a heart of gold" who gave her clothes and money when her home burned down last year.
More than 100 tips have been given to investigators, who have set up a hotline for people to call as police seek information about the crimes. A Cincinnati-area businessman also put up a 25,000-dollar reward for details leading to the capture and conviction of the killer or killers.
Robin Waddell, who owns the Big Bear Lake Family Resort just south of Piketon, said Christopher Rhoden often worked for him as a carpenter and helped out with his excavation business. He said Mr Rhoden was a nice guy whose children sometimes visited him while he was working.
"It's a large family," Mr Waddell said. "There's a lot of them and they've been in this community for generations. So this is affecting a lot of people."
Kendra Jordan, 20, said she often worked nights at a nursing home with Hanna Rhoden and described her as outgoing, funny and always smiling.
"If you were having a bad day, she'd be the first one to come up to you to question you about what was going on," Ms Jordan said. "She was amazing."
The exact timing of the shootings remains unclear. Authorities received the first 911 call shortly before 8am on Friday. The second came several hours later from another location.
Two of the crime scenes are within walking distance of each other along a sparsely-populated, winding road that leads into wooded hills from a rural highway. The third residence is more than a mile away, and the fourth home is on a different road, at least a 10-minute drive away.
Todd Beekman, who owns an outdoors shop a few miles from the crime scenes, said at least one customer came in to stock up on ammunition after hearing about the shootings, but he and others added that they were not concerned for their own safety because residents know and look out for each other.
"The word spread pretty fast, as it does in any rural area," Mr Beekman said. "Everybody's kind of their own brother's keeper down here."