The teacher who died, Mike Landsberry, appeared to be trying to stop the incident when he was shot dead, Miller said Tuesday.
"It almost appears like he tried to talk him down," he said.
True to his character, the former Marine, a popular math teacher at Sparks Middle School, rushed to help others when the shots erupted.
"That was the kind of person that Michael was," said his brother, Reggie Landsberry. "He was the kind of person that if somebody needed help, he would be there."
Landsberry was an Alabama native who graduated from high school in Reno, next door to Sparks, in 1986. After his stint in the Marine Corps, he got an education degree from the University of Nevada in Reno. He joined the Air National Guard in 2001, rising to the rank of master sergeant and serving as a cargo specialist in Kuwait and Afghanistan, the Guard said.
A Facebook memorial page for the teacher had more than 10,000 "likes" by early Tuesday. Thousands more honored him on a "Rest Easy Mr. Landsberry" page.
Returning to a national debate
The Nevada shooting comes almost a year after a gunman killed 26 people at Sandy Hook Elementary School in Newtown, Connecticut, igniting a nationwide debate over gun violence and school safety.
Since the Newtown shootings last December, proposed school security plans across the country have included arming teachers, adding armed security guards and bringing in bulletproof backpacks and white boards.
Some teachers have started taking self-defense and combat classes in case a shooter enters their school. One class teaches how to escape or take cover but focuses most of its four hours on how to fight and disarm an attacker -- something few educators have ever considered how to do.
Meanwhile, reports of school violence have continued.
Last week, a student at an Austin, Texas, high school killed himself in front of other students.
In August, a student at a high school in Winston-Salem, North Carolina, shot and wounded another student in the neck.
Another shooting took place at an Atlanta-area middle school in January, though no one was hit.
That same month, a California high school student wounded two people, one seriously.
The mother of a student killed in Newtown said Monday's shooting reinforces the need to find solutions to keep students safe.
"The unthinkable has happened yet again, this time in Sparks, Nevada," Nicole Hockley said in a written statement. "It's moments like this that demand that we unite as parents to find common sense solutions that keep our children -- all children -- safe, and prevent these tragedies from happening again and again."
But what those solutions are will remain fuel for ongoing debate.