A plaque sits under the fall leaves at Van Allen Hall, one of the few symbols of an afternoon of terror in 1991.
"We all remember in our own way," said Mary Hall Reno. "I don't think any Nov. 1 goes by and we don't think about what happened."
Reno is now the chair of the Department of Physics and Astronomy at the University of Iowa. On Nov. 1, 1991, Reno was an associate professor in the department, working at Van Allen Hall. That afternoon, she was on the building's fifth floor.
Doctoral graduate Gang Lu, 28, walked into the building that Friday afternoon, destined for the second floor. Upset that his dissertation did not win a prize, Lu met with faculty members, and started shooting.
Using a revolver, Lu shot and killed department chair Dwight Nicholson, professors Christoph Goertz and Robert Smith and fellow doctoral graduate Linhua Shan. Lu and Shan had once been roommates and Shan had won the academic prize that Lu wanted.
As light snow started falling on that overcast day, Lu then walked three blocks west, to Jessup Hall.
"My wife worked at Jessup," said R.J. Winkelhake, then chief of the Iowa City Police Department. Winkelhake raced over to Jessup Hall.
In that time, Lu shot associate vice president for academic affairs T. Anne Cleary and student Miya Rodolfo-Sioson, who was working in an office at Jessup Hall. Cleary died the next day and Rodolfo-Sioson was paralyzed from the neck down until her death in 2008.
Winkelhake said his wife believed the suspect headed towards a conference room in the building.
"I could see someone under a conference table," said Winkelhake. "I actually got on top of the conference table and had a shotgun aimed down at the person."
That person was Gang Lu, who had shot himself just before Winkelhake arrived. Lu died soon thereafter.
Now retired and living in Galena, Ill., Winkelhake said what happened in Iowa City 20 years ago left a mark on the entire state.
"Those things didn't happen in Iowa," said Winkelhake. "And they don't happen at a university campus. It happened there. There was a certain amount of innocence that was torn away by that violent act."
Because the shootings happened 20 years ago, so many of the undergraduates at the University of Iowa don't remember that day. The typical freshman or sophomore was not even alive on November 1, 1991.
Yet today's college students have grown up in an era of deadly school shootings -- Columbine High School in 1999, Virginia Tech in 2007, Northern Illinois in 2008.
"I grew up close to Northern Illinois, so, obviously the shootings were publicized," said Mallory Litzo, a sophomore from Crystal Lake, Ill. "But it's never really scared me. I feel really safe here."
Freshman Quentin Marquez of Glenwood even admitted he had never heard of the 1991 UI shootings until being approached about this story.
"After the effects of Columbine and Virginia Tech, it's something all college students think about, but it doesn't affect us on a day-to-day basis," said Marquez.
Back inside Van Allen Hall, the bound physics volumes from Dwight Nicholson still sit in his old office, the same room where Gang Lu shot and killed him. The room is dedicated to the four people killed that day.The UI is not planning any formal recognition to mark the 20-year anniversary of the tragedy.