Student Thomas Wing said he was walking out of the cafeteria after eating breakfast when he saw a gun.
He told CNN affiliate KOLO that Landsberry was trying to get the student to put the weapon down. After a gunshot, Thomas started running back toward the cafeteria. He heard another shot.
"I was thinking, oh my gosh, am I going to get out of this? Am I going to die?" he told KOLO. "My heart was pounding faster than I could run."
An emergency dispatch calls released by the Sparks police department indicate Landsberry was shot on the school playground.
One wounded student was shot in the stomach, and the other injured student was shot in the shoulder, Washoe County School District Police Chief Mike Mieras said. The two 12-year-old boys were both in stable condition Monday night, Miller said.
Authorities said that first responders were at the school just three minutes after the initial 911 calls.
"I think we were well-prepared. Everybody responded appropriately. I think our first responders did a heckuva job, but it's a sad day for the city of Sparks," Mayor Martini told CNN.
Shooting began early Monday morning
City officials said authorities received emergency calls from students and staff at the school about 7:15 a.m. about an active shooter on campus.
Authorities said students were taken to a nearby high school to meet their parents. School was canceled for the week at Sparks Middle School and for the day at nearby Agnes Risley Elementary, officials said.
"I was deeply saddened to learn of the horrific shooting at Sparks Middle School this morning," Nevada Gov. Brian Sandoval said in a statement. "My administration is receiving regular updates and the Nevada Highway Patrol is assisting at the scene. Kathleen and I extend our thoughts and prayers to the victims and those affected by these tragic events."
The shooting is one of several this year at a U.S. middle or high school. Last week a student at a high school in Austin, Texas, 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 occurred at an Atlanta middle school in January, the same month a California high school student wounded two people, one seriously.
The Nevada shooting also comes almost a year after a gunman killed 26 people at Sandy Hook Elementary School in Newtown, Connecticut, igniting nationwide debate over gun violence and school safety.
The mother of a student killed in December's shooting in Newtown said Monday's shooting was reminder of 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 statement. "Our thoughts and prayers are with the victims, their families, and the children of Sparks Middle School, who today came face to face with violence that no child should ever experience. 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."