University President John Peters told the crowd that two years later, the light of all five students still burns brightly.
On February 14, 2008, a gunman walked into a geology class and opened fire killing Ryanne Mace, Daniel Parmenter, Gayle Dubowski, Catalina Garcia and Julianna Gehant before killing himself.
Sunday afternoon, the victims' families placed wreaths at the reflection wall.
A number of students said they felt it was important to attend the memorials.
"I felt it was like a necessary presence. I have to be here because I was there for that day," said David Thomas, a junior.
"Even though I left, it's not something you forget. And it brought back a lot of emotions that I didn't think I would have," said Amanda Saucedo, an NIU graduate.
Sunday afternoon's ceremony took place at the 'Forward Together Forward Memorial Garden,' which was created to honor the victims. The name comes from the school's fight song.