Scott Stump TODAY contributor

Sparks, Nev. middle-schooler Jose Cazares and his mom, Marisela are "forever grateful" for a hero teacher they say saved the boy's life Monday.

A young student opened fire on the school's basketball court Monday, shooting and killing math teacher Mike Landsberry and wounding two students before taking his own life.

"I was hanging out with my friends, and then we heard a loud gunshot and we thought it was firecrackers," Jose Cazares told Matt Lauer on TODAY Tuesday as he recounted the chaos of the scene. "So then we looked back toward where we saw the noise, and we saw the kid pull out his gun and shoot the kid in the arm, so then they started running and I froze because he was aiming his gun right at my chest. And I looked at the gun and my chest like, 'He's going to shoot me.'

"I turned around and I ran. I heard a gunshot, and I thought he shot me. Then I looked back, and he shot a kid in his leg, arm and stomach."

Cazares and other witnesses said Landsberry quickly stepped forward and spoke to the boy. 

"(Landsberry) was telling him to stop and put the gun down, and then the kid, he yelled out 'No!' yelling at him, and he shot him," Jose said. "(Landsberry) was calm and he was holding out his hand like, 'Put the gun in my hand,' like to just stop."

Landsberry, 45, a National Guardsman and former Marine, died at the scene. Sparks Mayor Geno Martini said Landsberry served two tours in Afghanistan with the Nevada National Guard.

"I'm forever grateful for everything that he did," an emotional Marisela Cazares told Lauer. "Just grateful he was there to help our children out."

Jose heard one of the students pleading with the shooter, saying, "Why me?''

"(The shooter) didn't say nothing,'' Jose said. "He just kept on shooting them." 

After Landsberry was shot, Jose said he and several other students ran and hid, but the shooter found them when he heard one of the students crying loudly.

"He started yelling, 'If you guys say anything about me coming here, I'm going to shoot you,' so then he shot twice to the windows, and then it seemed like he was out of bullets, so then he left,'' Jose said. 

Landsberry's brother, Reggie, told NBC News that the 8th-grade teacher is survived by his wife, Sharon, and two of her children from a previous relationship.

"I want to say that they're in my thoughts and prayers today and for the rest of the days," said Marisela. "I hope that God gives them the encouragement that they need to go on. Mr. Landsberry, he sacrificed his life to take our kids into safety, and I thank him for that. He's a true hero."