Eighth grade math teacher Michael Landsberry, 45, tried to negotiate with the student to put the gun down.
"To hear he was trying to protect those kids doesn't surprise me at all," said Chanda Landsberry, who is married to Michael's younger brother, Reggie. "He could have ducked and hid, but he didn't. That's not who he is."
Deputy Chief of the Reno Police Department Tom Robinson lauded Landsberry's actions.
"In my estimation, he is a hero," Robinson said. "We do know he was trying to intervene."
Landsberry, who was described as a popular teacher, also served in the Nevada Army National Guard.
The identities of the shooter and the two injured, all believed to be boys between 12 and 14, were not released.
Authorities did say one of the injured boys had undergone surgery, and the other was "doing well" after receiving treatment at Renown Regional Medical Center.
Robinson declined to confirm how the suspect died, but did say law enforcement did not fire any shots. Twenty or 30 witnesses will be interviewed in an attempt to determine a motive and whether the young gunman was targeting specific victims.
School administrators said classes have been canceled for the rest of the week and counselors have been brought in to help students and staff cope.