More than a week after four University of Idaho students were slain in the same house they shared near campus, police continue to search for answers.

The four students killed – Ethan Chapin, 20; Kaylee Goncalves, 21; Xana Kernodle, 20; and Madison Mogen, 21 – were discovered in a Moscow, Idaho home on Nov. 13 shortly before noon after police received a 911 call reporting an unconscious person. Police say that the phone used belonged to on of two surviving roommates, but that someone else made the call. Police have declined to identify the caller.

Two surviving roommates were present when police arrived and are believed to have slept through the attacks. Police said the surviving roommates are not suspects.

No arrests have been made.

"This incident has shaken our community and has continued to shake our community," Moscow Police Chief James Fry said at a news conference. "It is a complex and terrible crime and it will take soime time to resolve."

Moscow is a tight-knit community of around 25,000 people, sharing a border with Washington state, with the local university enrolling 11,000 students.

"We cannot say there's no threat to the community and as we have stated, please stay vigilant, report any suspicious activity and be aware of your surroundings at all times," Police Chief Fry said Wednesday, at a news conference.

According to polcie, Chapin and Kernodle, who were dating, attended a party at the Sigma Chi fraternity house from 8 p.m. to 9 p.m. Saturday. Goncalves and Mogen were at a local sports bar between 10 p.m. and 1:30 a.m., later seen ordering from a popular food truck downtown.

All four victims returned home by 1:45 a.m.

In an interview with ABC World News Tonight, Goncalves's sister Alicia said the residence was known to be a "party house."

The coroner who conducted the autopsies of the victims concluded that the four friends were most likely asleep at the time of the attack — adding that some of the victims showed signs of fighting back.

The university and surrounding community remain in shock following the attack, with a vigil scheduled on campus for Nov. 30. Classes were canceled leading up to the Thanksgiving holiday, and the university is said to be mulling moving the rest of the semester to a virtual format.