Davis, Mason's mother, told CNN that she grieves for the shooter's family.
"They lost their son, their baby," Davis said. "They're 12-year-old boys ... they have no idea what they're doing."
'Keep these guns out of kids' hands'
Reyes took his parents' handgun to school, a federal law enforcement source said. Sparks Deputy Police Chief Tom Miller said Tuesday that authorities weren't positive where the gun came from, but believe it belonged to the boy's parents.
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.
"It's really mainly about educating these kids about what guns can do, and also keeping your guns locked up," Davis said.
"I own a gun, but I also own a safe it goes in," she said. "That's why my whole thing is: Keep these guns out of kids' hands. Protect your guns -- that protects your kids."
Landsberry 'fun to hang around'
Landsberry was an Alabama native who graduated from high school in Reno, next door to Sparks, in 1986. After a 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.
Mason said Landsberry was never his teacher, but losing him is hard. He would visit Landsberry during lunch "because he was funny and friendly, and fun to hang around," he said.
"(Students) loved him so much," Mason said.
Davis said she hoped the hospital would release Mason later Thursday or Friday. She said she and her son will have a conversation about when -- and whether -- he will return to the school.
"We're going to talk about that. ... He would have a lot of support there," she said.