Kendrick Castillo, student killed in Colorado high school shooting, was just 3 days from graduating

An 18-year-old student who died in Tuesday's mass shooting at a Colorado charter school was just three days away from his graduation.

Kendrick Castillo, a senior at STEM School Highlands Ranch in suburban Denver, attempted to disarm one of the two suspects who entered his British Literature classroom armed with handguns around 2 p.m., according to fellow student Nui Giasolli. He was shot and killed in the process.

"The next thing I know, [the shooter] is pulling a gun and he’s telling nobody to move, and that’s when Kendrick lunged at him," she told TODAY. "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."

Castillo, a decorated, four-year member of the school's robotics team, was the sole fatality of the shooting, which left eight others injured. The victim's father, John Castillo, spoke out on his son's tragic death on Wednesday.

"He was the best kid in the world," the bereaved father said through tears. "It doesn’t surprise me. 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," he added. "His character is about protecting people, helping people."

Photos from the scene:

Another student later identified as Brendan Bialy, a senior who is enrolled in the Marine Corps Delayed Entry Program, was also heralded for his brave intervention during the attack, NBC News reports.

"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.

Two suspects, an adult male identified as 18-year-old Devon Erickson and a juvenile female whose identity has not been released, are in police custody, the Douglas County Sheriff's Office said. The investigation is ongoing, and a possible motive has not yet been released.