Jason Seaman, 29, a former football player at Southern Illinois University and a 13-year-old female student were wounded by gunfire in the shooting, which broke out around 9 a.m. on Friday morning at a middle school in Noblesville, a town of 62,000 just northeast of Indianapolis.
Police said that a student asked to be excused from class at Noblesville West Middle School and then returned with two handguns and opened fire.
Students and parents of students from the school told news outlets that Seaman helped stop the shooter.
"Our science teacher immediately ran at him, swatted a gun out of his hand and tackled him to the ground," Seventh-grader Ethan Stonebraker told the Associated Press. "If it weren't for him, more of us would have been injured for sure."
Stonebraker described the incident in more detail to ABC News, saying that Seaman threw a basketball at the shooter.
"Immediately Mr. Seaman was yelling and running right at him and tackled him to the ground," Ethan said. "I was trying to stay crouched behind the back table, but also see what's going on and that's when [Mr. Seaman] was running right at him with this arms in front of him, and then he just tackled him against the wall. Then they were on the ground after [Mr. Seaman] swatted the gun from him and he just laid on the shooter so he couldn't do anything."
Police said they arrested the shooter and said the "situation resolved fairly quickly," but did not confirm the accounts of Seaman's reaction or details about how they arrested the shooter. A police officer assigned to the school was on duty and in the building, they said.
"Wait 'til one day we can tell you that story," Indiana State Police Superintendent Doug Carter said, according to the AP. "You'll be proud of them, too."
Seaman released a statement published by local media outlets, thanking the police and emergency responders for their action and care.
"I want to let everyone know that I was injured but am doing great," the statement said. "To all students, you are all wonderful and I thank you for your support. You are the reason I teach."
His mother, Kristi J. Hubly Seaman, said in a Facebook post that he had been shot three times: once through the abdomen, and one on his hip and forearm. Police said Seaman was in good condition as of Friday night; the injured student, who has not been publicly identified was in critical condition.
Seaman's brother, Jeremy, told the IndyStar that Seaman had two young children. He said he wasn't surprised by the reports of his brother's bravery.
"It's not surprising, to be honest," he said. "He's not really ever been the person to run away."
Seaman played for Southern Illinois from 2007 to 2010 as a defensive end, notching 88 tackles and eight sacks with two forced fumbles in 47 games for the Salukis. He was a three-sport athlete when he attended high school in Mahomet, Ill. Jeremy told the newspaper.
"He's familiar with struggle and adversity," he said.
Nick Hill, who is the head coach at Southern Illinois and played as a teammate of Seaman's, said he was a "great teammate, one of the team's hardest workers."
"You could always trust him to do the right thing," Hill said.
Gov. Eric Holcomb, R, released a statement saying his "thoughts are with all those affected by this horrible situation."
Molly Miles, a Noblesville High School freshman, told the IndyStar that she remembered Seaman telling the class that he would keep them safe in the event of a shooting.
"I especially remember that he would throw himself on top of the shooter if he had to," she said. "Which he proved today. He always said that he was willing to sacrifice himself before he was willing to let anything happen to his students."
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)