It doesn't take the presence of a "weapon" to be a situation where you should be in fear for your life. There are plenty of ways to get killed by somebody who is "unarmed".
The victims are college students. As usual on most campuses they can't CCW so they are obviously unarmed prey to criminals and the criminals know it. In this case it may have saved a life. Six on two are mighty poor odds even when the two are big football players.
Personally, if I am attacked by someone "unarmed", I would consider myself in deadly peril and fear for my life and respond accordingly - even if it were just some rambunctious "yutes" trying to get another free ObamaPhone (strangely enough, no description of the killers in the article so one can rightly assume their racial makeup). But the local Gun Free Zone Rules assured these guys never had a decent chance despite their muscles and conditioning.
...students had gathered for an impromptu vigil during the day. Young people shared condolences on a large remembrance banner... the student health center hosted professional counselors all day.... (see tagline)
Not an update but it the above video press conference they at least describe the suspects.