MOSCOW, Idaho — Three days after a gruesome mass killing left four students dead near the University of Idaho, the authorities said Wednesday that they still had no suspect and could not assure that there was no lingering threat to the community.
Investigators have not recovered a murder weapon but believe the four students — all friends who had seemed to be spending a typical Saturday night in the college town of Moscow — were stabbed to death. The authorities asked people to remain vigilant, watch out for each other and come forward with any information that could help bring a perpetrator to justice.
“These murders have shaken us to our very core,” Col. Kedrick Wills, the director of the Idaho State Police, said at a news conference.
Chief James Fry of the Moscow Police Department said there was no sign of forced entry into the home, a large rental just outside of campus, and that the door was found open after police officers were called to the scene on midday Sunday, apparently many hours after the killings had occurred.
Chief Fry said two other people were in the home at the time of the attack who were not injured, although he declined to say whether they witnessed the killings or to disclose what they shared with investigators. He said it had not been a hostage situation, but said the authorities had not been able to identify who might have carried out the crime.
“We do not have a suspect at this time,” the chief said. Whoever committed the crime, he warned, “is still out there.”
Cathy Mabbutt, the Latah County coroner, said in a text message on Wednesday afternoon that she was still conducting the autopsies and would be doing so until later in the evening. But as of yet, she said, she had found nothing surprising nor anything to contradict the earlier belief that the victims had been stabbed to death.
The authorities have said the totality of the evidence they have indicates the attack was targeted, identifying the victims as Ethan Chapin, 20; Madison Mogen, 21; Xana Kernodle, 20; and Kaylee Goncalves, 21.
The four friends appeared to have been having a typical weekend night in the community, with Mr. Chapin and Ms. Kernodle at a party while Ms. Goncalves and Ms. Mogen had gone to a downtown bar before they gathered at the house.
In a recorded video livestream from a food truck downtown, Ms. Goncalves and Ms. Mogen could be seen around 1:45 a.m., with one of them ordering food. They mingled on the sidewalk until the food was ready, then departed.
Mr. Fry said investigators had seen the video, saying it had been helpful to place the students at that time of night as authorities work to build a timeline of events.
The community fear in the aftermath of the killings has led many students to leave town. Officials had been trying to calm nerves by saying that they did not believe the broader community was at risk. But on Wednesday, Chief Fry’s message changed.
“We cannot say that there is no threat to the community,” he said.
In one possible clue to the investigation, Scott Jutte, general manager of Moscow Building Supply, confirmed a report in The Idaho Statesman that police officers had visited the store more than once in recent days to ask whether it sold Ka-Bar tactical knives. The store does not sell that style of knife.
Alivea Goncalves, Kaylee’s older sister, said the family has no idea who could have committed such a crime.
“That’s why we believe the most important thing right now is tips,” she said. “If you saw them at all, even if it was a totally normal interaction, call it in. If you saw anything the next day or in a trash can or even a weird feeling, call it in.”
At a candlelight vigil on Wednesday evening in Coeur d’Alene, Idaho — an area where three of the victims were from — hundreds of people gathered at a park on the edge of Lake Coeur d’Alene to share memories of the victims.
“We just want people to know who they were, that they were just a huge part of this community,” said Daisy Couch, 22, who went to high school with Ms. Mogen.
Angela Navejas, whose daughter was also friends with Ms. Mogen, called the victims “some of the brightest stars I’ve ever known in my life.”
“They were wild and carefree and loving,” she said.
At Wednesday’s news conference in Moscow, Scott Green, the president of the University of Idaho, teared up as he spoke about the case. He said the crime was beyond comprehension, and the entire campus has been grieving for the students.
“Their loss has been devastating,” he said.
Serge F. Kovaleski contributed reporting. Susan C. Beachy and Sheelagh McNeill contributed research.