On Tuesday afternoon, two students, one male and one female, opened fire on two classrooms at the STEM School Highlands Ranch in Colorado. The perpetrators, who were armed with handguns, killed one student and injured eight others. Authorities apprehended both suspects and took them into custody.

Douglas County Sheriff Tony Spurlock told reporters Wednesday that the sole student killed in the attack was Kendrick Castillo, an 18-year-old senior. Castillo was a member of the school's award-winning robotics team and just three days away from graduation. His classmates remember him as a nice kid, a jokester, and a hero, who reportedly lunged at one of the shooters, sacrificing his life to save others.

Student Niu Giasolli witnessed the attack in her British literature class and described Castillo's actions to NBC's Today show. "The next thing I know is [the shooter] is pulling a gun and he’s telling nobody to move, and that’s when Kendrick lunged at him," Giasolli said. "And he shot Kendrick, giving all of us enough time to get underneath our desks, to get ourselves safe, and to run across the room to escape."

John Castillo, Kendrick's father, told The Denver Post that his son's sacrifice didn't surprise him. "He was the best kid in the world," Mr. Castillo said through tears. "He cared enough about people that he would do something like that, even though it’s against my better judgment. I wish he had gone and hid, but that’s not his character. His character is about protecting people, helping people. I had a hard time accepting that."

Mr. Castillo said his son loved science, hunting, fishing and automobiles.

Kendrick Castillo was not the only student who courageously confronted the shooters. On Today, Giasolli also thanked "Brendan Bialy, Jackson Gregory, and Lucas Albertoni [for being] some of the kids that were brave enough to bring [the shooter] down so that all of us could escape and all of us could be reunited with our families. They were very heroic. I can’t thank them enough."

Sheriff Spurlock did not name any of the students who reportedly tackled the suspects during his press conference. However, he confirmed "we are going to hear about very heroic things that have taken place at the school," as the investigation continues. "I suspect as the detectives get further interviews from them, we’re going to find that there were much more heroic things," Spurlock said.

Roughly 1,500 students attend STEM School Highlands Ranch, a "free, public charter school" for grades K-12. The facility is located about 15 miles from Denver, and just six miles from Littleton, where the Columbine school shooting took place. Last month, an armed Florida teen 'infatuated' with the Columbine shooting who threatened Colorado schools was found dead near Mt. Evans.

Just a week ago, a gunman opened fire at the University of North Carolina in Charlotte. He killed two people, 19-year-old Ellis Parlier and 21-year-old Riley Howell, while wounding four others. Like Castillo, Howell confronted the shooter, sacrificing himself to save others.

On Tuesday afternoon, two students, one male and one female, opened fire on two classrooms at the STEM School Highlands Ranch in Colorado. The perpetrators, who were armed with handguns, killed one student and injured eight others. Authorities apprehended both suspects and took them into custody.

Douglas County Sheriff Tony Spurlock told reporters Wednesday that the sole student killed in the attack was Kendrick Castillo, an 18-year-old senior. Castillo was a member of the school's award-winning robotics team and just three days away from graduation. His classmates remember him as a nice kid, a jokester, and a hero, who reportedly lunged at one of the shooters, sacrificing his life to save others.

Student Niu Giasolli witnessed the attack in her British literature class and described Castillo's actions to NBC's Today show. "The next thing I know is [the shooter] is pulling a gun and he’s telling nobody to move, and that’s when Kendrick lunged at him," Giasolli said. "And he shot Kendrick, giving all of us enough time to get underneath our desks, to get ourselves safe, and to run across the room to escape."

John Castillo, Kendrick's father, told The Denver Post that his son's sacrifice didn't surprise him. "He was the best kid in the world," Mr. Castillo said through tears. "He cared enough about people that he would do something like that, even though it’s against my better judgment. I wish he had gone and hid, but that’s not his character. His character is about protecting people, helping people. I had a hard time accepting that."

Mr. Castillo said his son loved science, hunting, fishing and automobiles.

Kendrick Castillo was not the only student who courageously confronted the shooters. On Today, Giasolli also thanked "Brendan Bialy, Jackson Gregory, and Lucas Albertoni [for being] some of the kids that were brave enough to bring [the shooter] down so that all of us could escape and all of us could be reunited with our families. They were very heroic. I can’t thank them enough."

Sheriff Spurlock did not name any of the students who reportedly tackled the suspects during his press conference. However, he confirmed "we are going to hear about very heroic things that have taken place at the school," as the investigation continues. "I suspect as the detectives get further interviews from them, we’re going to find that there were much more heroic things," Spurlock said.

Roughly 1,500 students attend STEM School Highlands Ranch, a "free, public charter school" for grades K-12. The facility is located about 15 miles from Denver, and just six miles from Littleton, where the Columbine school shooting took place. Last month, an armed Florida teen 'infatuated' with the Columbine shooting who threatened Colorado schools was found dead near Mt. Evans.

Just a week ago, a gunman opened fire at the University of North Carolina in Charlotte. He killed two people, 19-year-old Ellis Parlier and 21-year-old Riley Howell, while wounding four others. Like Castillo, Howell confronted the shooter, sacrificing himself to save others.