Two other roommates were home while four University of Idaho students were being violently murdered with an edged weapon, police have said.
Local police chief James Fry revealed at a press conference on Tuesday that there were other people in the house at the time of the murders, which have shocked the small college community of Moscow, Idaho.
He said that the housemates were unharmed and that they were still present when police arrived hours later. He added that detectives do not believe there was any hostage situation.
The information only raises new questions about what happened after Ethan Chapin, Madison Mogen, Xana Kernodle, and Kaylee Goncalves returned to the house from partying in the small hours of Sunday morning.
Police say the four students were violently killed some time between 3am and 4am using an "edged weapon", promising further details once autopsies have been completed.
Sources close to the investigation told The Daily Mail that it was the worst crime scene they had ever seen, and photos showed blood dripping down to the ground from behind the wooden exterior walls of the house.
Nevertheless, when asked by a reporter whether the victims' housemates were home at the time of the murder, Mr Fry said: "There was other people at home at that time. But we're not focusing just on them, we're focusing on everybody."
The reporter followed up: "Was it a hostage situation?" Mr Fry responded: "Not it was not." He added that the housemates were not injured, and that both were still at the house when police arrived.
When another reporter asked why it took so long for anyone to call 911 when there were surviving witnesses on the scene, Mr Fry said: "I don't think I ever said that they were witnesses; I said they were there. We don't know why that call came in at noon, and not in the middle of the night."
He declined to say whether one of the housemates called 911, citing a need to protect the integrity of the investigation. He also declined to say what the housemates might have told police officers.
Nor would he divulge whether the victims were all found in the same part of the house. However, he did say there was no sign of robbery, or anything taken from the house.
Asked whether there had been a party at the house, he said: "Not that we know of. Not at the home."
