DEKALB COUNTY, Ill. — A solemn ceremony in west suburban Dekalb marked the 15th anniversary of a deadly mass shooting at Northern Illinois University.

Five students were killed — Gayle Dubowski, Catalina Garcia, Julianna Gehant, Ryanne Mace and Daniel Parmenter — after a gunman took a shotgun and three pistols into the university’s Cole Hall auditorium on Feb. 14, 2008 and shot 22 people in all.

The gunman later took his life.

Shooting survivor Harold Ng wrote a book to come to terms with the tragedy. The author suffered a non-life-threatening wound but said the emotional toll is the hardest to cope with.

“Why did it happen?” Ng asked. “You don’t expect it to.”

Patrick Korellis and other shooting survivors returned Tuesday to the memorial site on NIU’s campus. The horrific memory of what happened in 2008 remains vivid in people’s minds.

“A guy kicks the stage door open, doesn’t say a word, and just starts shooting at us,” Korellis recalled.

Bells rang at precisely 3:06 p.m., the exact time the gunman opened fire more than a decade ago.

Korellis, in all the commotion, said he did not immediately know that he had suffered a wound to his head while escaping from Cole Hall as the gunman reloaded. But the shooting survivor said there are see memories he will never forget.

“I remember where I was sitting,” Korellis said. “I remember where I was shot and when I started bleeding.”