(CNN) -- The timing and location of the Arapahoe High School shooting make it certain that memories of other mass shootings won't go away.
Arapahoe happened one day before the anniversary of the Newtown, Connecticut, school shooting. It occurred within 17 miles of two other infamous Colorado gun rampages—the Aurora movie theater shooting and Columbine High.
The shooter, identified as 18-year-old Karl Halverson Pierson, shot one student before turning the gun on himself and taking his own life, Sheriff Grayson Robinson said. Arapahoe is in suburban Denver.
For some people, the tragedies are linked. A mother who picked up her child from Arapahoe shared her family's anguish.
"My husband was a freshman at Columbine. He's freaking out right now," she told told CNN affiliate KCNC. "It's bringing back horrible memories of that. And it's just way too close to home."
Newtown had hoped to quietly remember what happened on December 14, 2012. Adam Lanza killed 20 first-graders and six adults at the now-demolished Sandy Hook Elementary in what was the second-deadliest school shooting in U.S. history, following the April 2007 slaying of 32 people at Virginia Tech.
City leaders asked journalists to stay away and give the community a chance to grieve, and many news organizations had said they would honor that request in some manner. It's not known if they'll stay away in light of Arapahoe.
Newtown started an intense national conversation on gun safety but led to little legislative change. Connecticut authorities released a report last month saying they don't know what motivated Lanza, who briefly attended the school. He killed his mother before going to the school and killed himself.
Arapahoe High is about 16 miles from Aurora, Colorado, where a gunman killed 12 people and wounded 58 on July 20, 2012, in a movie theater screening a new Batman film.
James E. Holmes, then 24, was taken into custody outside the movie theater. Police said he was dressed head-to-toe in protective tactical gear and sprayed the theater with bullets from an AR-15 rifle, a 12-gauge shotgun and at least one of two .40-caliber handguns police recovered at the scene. Holmes had colored his hair red and told police he was "the Joker," police said.
Jury selection for Holmes' trial was scheduled to begin in February, but the judge said that process could take eight months. The judge vacated the trial date and has not set a new date.
Jordan Ghawi, whose sister was killed in Aurora, shared his feelings on Twitter: "Sitting here at the FD listening to @donlemon on @CNN as my hands are literally shaking. Rush of emotions ranging from solidarity to anger.
"17 miles away from where my sister was killed. My thoughts are once again with Arapahoe Co and the State of Colorado."
On April 20, 1999, the Columbine High mass shooting happened about 8 miles from Arapahoe High. Columbine students Eric Harris and Dylan Klebold killed 12 students and one teacher before fatally shooting themselves in the school library.
SWAT teams entered Columbine 47 minutes after the shootings started. Five hours passed before law enforcement declared the school under control.
In contrast, the first sheriff's deputies and police officers arrived at Arapahoe and entered almost immediately after the shooting was reported, Sheriff Grayson Robinson said. It is not known if law enforcement altered their protocols because of Columbine.
Harris and Klebold made home videos before the attack making references to what they were going to do and apologizing to their parents for it.
In the intervening years, Columbine has become a synonym for unfocused, violent teenage rage.
Arapahoe is part of the Littleton Public School district and Columbine part of the Jefferson County School District.