Police in Moscow, Idaho, said Sunday that other friends were in the house when a 911 call was made following the fatal stabbings of four University of Idaho students a week ago, but couldn't say how many.
The 911 call was placed last Sunday at 11:58 a.m. reporting an unconscious person, police said. Two victims were found on the second floor and two on the third floor, according to police.
Two female surviving roommates were at the house at the time and were not hurt, Moscow Police Chief James Fry has said. Police said Friday that they don't believe the two surviving roommates are involved in the crime, which authorities reiterated Sunday.
The 911 call was made from one of the two surviving roommates' phones, according to police, who would not disclose who made the call but said that person was not considered the killer.
There are no suspects in custody.
MORE: Idaho college murders: 2 surviving roommates not believed to be involved, police sayThe victims, who were killed in a house near campus in the early morning hours on Nov. 13 and found hours later, were identified as Ethan Chapin, 20, of Conway, Washington; Madison Mogen, 21, of Coeur d'Alene, Idaho; Xana Kernodle, 20, of Avondale, Arizona, and Kaylee Goncalves, 21, of Rathdrum, Idaho.
The coroner has identified all four victims and their cause of death as homicide by stabbing, police said Sunday.
Police have said the victims were likely sleeping at the time of the attack, and each was stabbed multiple times, citing the coroner. Some victims had defensive wounds, but there were no signs of sexual assault, police said.
University of Idaho President Scott Green on Sunday addressed safety in the wake of the horrific incident, saying they have ramped up security and are working to accommodate students who don't feel safe on campus.
"We fully appreciate and share the frustration of our students, employees, parents and community members who continue to push for answers. While we wait for answers in the investigation, we've ramped up our security safety practices in our listening to students and supporting them in any way possible," Green said.
"The police continue to inform us that they believe this was a targeted attack. But we recognize this is not good enough for some of our students who will want to complete their semester remotely until the person who committed the crime is in custody," he continued.
"In addition to the campus-wide precautions being taken, we offer the following security, safety and security feature features in our residence halls," Green said. "We will continue our Safe Walk available 24 hours a day, seven days a week. All residence halls are locked 24 hours a day and only accessible by students that live in the building. All guests must be accompanied by a resident of the building."
Police on Friday also released a map and timeline of the whereabouts of the victims in the hours before the killings.
Goncalves and Mogen -- lifelong best friends -- were in downtown Moscow the night of Nov. 12 while Chapin and Kernodle -- who were dating -- were at the Sigma Chi house, police said.
At about 1:40 a.m., Goncalves and Mogen were seen on video at the Grub Truck food vendor, and then they got a ride home from a private party, arriving at 1:45 a.m., police said. Authorities said Friday that the man seen in the Grub Truck surveillance video with the victims is not believed to be involved in the crime.
Chapin and Kernodle also got home around 1:45 a.m., police said. Chapin didn't live in the house where they were killed but was sleeping over with his girlfriend, according to his mother, Stacy Chapin.
Police are searching for leads and urge anyone who saw "suspicious behavior, has video surveillance, or can provide relevant information" to call the tip line at 208-883-7180 or email tipline@ci.moscow.id.us.
ABC News' Marilyn Heck, Izzy Alvarez and Flor Tolentino contributed to this report.