"I cannot express enough appreciation for Mr. Landsberry," Washoe County School District Superintendent Pedro Martinez said about the 45-year-old ex-Marine. "He truly is a hero."
"His actions yesterday I believe saved the lives of many children," added Col. Jeffrey Burkett, commander at the Nevada Air Guard's 152nd Airlift Wing where Landsberry served.
Police said they believe the shooter at one point tried to enter the school but couldn't open the door because of emergency lockdown procedures.
After killing Landsberry, the boy fired at a second student, hitting him in the abdomen. He then shot himself in the head.
The two 12-year-old boys who were wounded are in stable condition and recovering.
Parents clung to their children at an evacuation center shortly after the shooting while the community struggled to make sense of the latest episode of schoolyard violence, which happened less than a year after the Newtown, Conn., massacre.
Sparks, just east of Reno, has a population of roughly 90,000.
Under Nevada law, it is illegal to allow anyone under 18 to handle a gun without supervision. The offense rises to a felony if there was substantial risk the child would use the firearm to commit a violent act. However, the law doesn't apply if the gun was stored securely or if the child obtained the weapon unlawfully.
Landsberry was married, had two stepdaughters and coached several youth sports. He also served once in Kuwait and two tours in Afghanistan with the Nevada National Guard and was well-known in the school community. He served in the Marine Corps from 1986-90 and was stationed in Camp Lejeune, N.C., and Okinawa, Japan, according to military records.
His bravery came as no surprise to his fellow airmen.
"That's who he was," Chief Master Sgt. James Ross told reporters at the air base in Reno on Tuesday.