"We have accounted for all of those involved, and there is no danger," Stephen McCausland, spokesman for the state Department of Public Safety, said Tuesday.
Investigators said they believe that the suspect, identified by state police as Christian Nielsen, was responsible for all four deaths near southern Maine's Sunday River ski resort and that there are no other victims.
It wasn't immediately clear who the four victims were or how they were connected to the Black Bear Bed & Breakfast, where the women's bodies were discovered Monday evening.
Nielsen, who had been renting a room at the Black Bear, knew at least two of the victims, McCausland said. Police would not comment on the circumstances or possible motive for the killings, and autopsies were being conducted on the bodies.
The remains of the fourth victim, a man, were found in a wooded area north of nearby Grafton Notch State Park.
Nielsen worked at another bed and breakfast in the area, the Sudbury Inn in Bethel, and was being held at the Oxford County Jail on one count of murder. Additional murder charges were expected.
The phone rang unanswered Tuesday at the Black Bear, an 1830s farmhouse on the Sunday River that was converted into a six-room bed and breakfast. It is near Newry, about 75 northwest of Portland and just across the state line from New Hampshire.
Nancy White, co-owner of the Sudbury Inn, was stunned to learn that the cook she and her husband had hired this summer had been arrested for murder.
"He's a reliable, soft-spoken employee," she said.
Nielsen's mother, Patricia Kenyon, lives in the nearby town of Upton but was not at home and unavailable to talk to the media, according to a man who answered her phone.