A U.S. Marine recruit and other teenagers rushed one of the shooters at a Colorado school, helping to disarm him, according to police and witnesses.

One of the students, Kendrick Castillo, 18, died while lunging at the shooter, according to a classmate at STEM School Highlands Ranch in a Denver suburb. Eight other students were injured in the shooting Tuesday.

Kendrick Castillo was fatally shot at a STEM School in Highlands Ranch, Colorado. John Castillo / via Facebook

"We're going to hear about very heroic things that have taken place at the school," Douglas County Sheriff Tony Spurlock said Wednesday.

Two suspects, both students, are in custody — Devon Erickson, 18, and a juvenile. Erickson made an initial court appearance on Wednesday and prosecutors are expected to file charges against him on Friday.

Authorities identified a second suspect as a juvenile female, but a public defender clarified that the juvenile prefers to use male pronouns. NBC News is not identifying the underage suspect, who has not yet been charged.

One of the teens involved in trying to take down a shooter was Brendan Bialy, a senior who plans on joining the Marines after he graduates in a few weeks.

The class was watching a movie when the shooter came in, Bialy told NBC News. He says that's when he, Castillo and another classmate, Josh Jones, lunged at the gunman in an effort to disarm him.

"I didn’t really think about it, it’s just like a very spur of the moment. I was afraid when it happened, absolute fear, but once that half second of fear struck I just...my body moved," Bialy told NBC News Wednesday.

Bialy said that he was very close to Castillo, someone he was friends with for all of high school. Since Castillo's voice is gone now, he felt he knew his friend well enough to try to keep his friend's memory alive, Bialy said.

"As the trend is now to propagate the name of the shooter, shooters and their intents just kind of glorifies it, if anything inspires other people," Bialy said. "So in this happenstance, the absolute legend of the events of yesterday, Kendrick Castillo is the name I think should not go away to the sands of time."

Bialy is enrolled in the Marine Corps Delayed Entry Program, the 8th Marine Corps District confirmed in a statement.

"Brendan’s courage and commitment to swiftly ending this tragic incident at the risk of his own safety is admirable and inspiring," the 8th District Marines said.

Brendan Bialy, who is enrolled in the Marine Corps Delayed Entry Program, helped subdue a shooter at the STEM School in Colorado. Brendan Bialy / via Instagram

Senior Nui Giasolli told the "Today" show that she was in class when one of the gunmen, a classmate, entered and suddenly drew a gun.

“That’s when Kendrick lunged at him, and he shot Kendrick,” Giasolli said, “giving all of us enough time to get underneath our desks, to get ourselves safe, and to run across the room to escape.”

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Giasolli thanked Bialy and the other students who rushed the shooter. They "were brave enough to bring him down so that all of us could escape and all of us could be reunited with our families.”

The shooting came one week after two people were killed and four others injured in a shooting at the University of North Carolina at Charlotte.

One of the slain U.N.C. students, Riley Howell, 21, challenged the shooter giving police extra time to confront him. The local police chief hailed him as a hero while his family said they were "beyond proud."