He was a high school senior, set to graduate this week.
But instead of celebrating Kendrick Castillo's graduation, the family of the 18-year-old American will be mourning his death.
Castillo, a senior at STEM School Highlands Ranch, Colorado, was killed in a classroom on Tuesday (Wednesday NZT) in a shooting that police say was carried out by a pair of his classmates: 18-year-old Devon Erickson and younger classmate Maya McKinney, known as Alec. Eight other students were injured in the shooting.
His father, John Castillo, said his life will never be the same after Kendrick's death. "I don't know what I'm going to do without him in our lives," he told NBC News. "I don't know why this happened to such a good kid."
The charter school campus has more than 1800 students, including small children who streamed out of the school weeping and with their arms raised to escape the danger.
Nui Giasolli was in her British literature class when she said a classmate began shooting.
She told NBC's Today that Castillo lunged at the man who opened fire and was shot. Several other classmates also worked to take the shooter down, she said.
"The next thing I know, he's pulling a gun and telling nobody to move," Giasolli said. "That's when Kendrick lunged at him, and he shot Kendrick, giving us all enough time to get underneath our desks to get ourselves safe, to run across the room to escape."
Another student, Brendan Bialy, wrestled the gun from the shooter's hand and students subdued him.
Castillo sprang into action against the shooter "and immediately was on top of him with complete disregard for his own safety," said Bialy, a close friend.
Bialy smiled as he recounted the struggle with the shooter to reporters, saying that he wanted to focus on the positive: "They completely and utterly failed in a matter of half a minute," he said of the attackers.
He added, "What I saw yesterday was the absolute best of people".
Bialy would not identify the third student who helped subdue the gunman but the family of Jason Jones put out a statement saying he was shot twice while disarming one of the attackers.
A member of the school's robotics club and a relentless tinkerer, Castillo had an infectious smile and gentle sense of humour, according to friends.
He worked part-time at a local manufacturing company that had offered him a job after an internship because he was such a standout employee.
"To find he went down as a hero, I'm not surprised. That's exactly who Kendrick was," said Rachel Short, president of the company, Baccara.
Cecilia Bedard, 19, had known Castillo since elementary school and said he was always friendly, modest and excited to help people.
"He was amazing," Bedard said. "He was honestly the sweetest kid I ever met. Never said a mean joke."
SHOOTING IN SHADOW OF COLUMBINE
The shooting happened not far from Columbine High School, a community still on edge after marking the 20th anniversary of a shooting there that shocked the United States and the world.
District Attorney George Brauchler, who grew up in the region, said at a news conference Wednesday morning that if someone had told him that in 20 years the region would endure mass shootings, he would have thought them crazy.
"These are aberrant acts," he said, despite the fact that several attacks have happened within a 33-kilometre radius.
Now is the time to mourn and to weep, he said, but the people of Colorado are resilient: "My kids are going to go to school today," he said, acknowledging the conversations anxious parents are having. "I recommend everyone else send their kids, too."
Details of the shooting began to emerge on Wednesday.
Within two minutes, the first deputy arrived and confronted a gunman, Douglas County Sheriff Tony Spurlock said. Deputies struggled with the suspects before taking them into custody.
Neither suspect was injured, he said, and no gunfire was exchanged with them. One of the suspects was restrained by the armed private security officer who had been hired to protect the school, Spurlock said.
"I have to believe the quick response of the officers that got inside that school helped save lives," Spurlock said.
About 600 students were in the section of the school where the attack occurred.
ACCUSED SHOOTERS IN COURT
The two suspects in the school shooting have appeared in court.
Court records listed one the defendant as Maya McKinney, but a public defender said that his client used male pronouns and was named Alec.
McKinney appeared in court shackled at the wrists and ankles. He responded to the judge's questions in a clear but quiet voice, saying, "Yes, your honour" and "No, your honour." His mother sat with him.
District attorney George Brauchler said he had not decided whether to file adult charges. He said McKinney was 16, the youngest age at which Colorado law allows prosecutors to file adult charges without a judge's review.
McKinney was being held on suspicion of murder and attempted murder and is due back in court on Friday (Saturday, NZT).
The second shooting suspect, Erickson, made his first court appearance, bowing his head during much of the proceedings with his dark hair streaked with purple covering his eyes.
The 18-year-old nodded frequently in answering the judge's questions but at one point the judge requested a verbal answer to whether he had any questions. He simply replied "No."
Authorities were in the early stages of interviewing witnesses and learning what happened, the sheriff said. "We are going to hear about very heroic things that happened at that school."
INTENSIVE CARE
Five of the students who were shot have been released from hospitals, Spurlock said, and three remain in intensive care.
The wounded students were 15 years old or older, he said. All nine of the students harmed were shot at the school, Spurlock said.
The Denver region has been on edge after the 20th anniversary of the Columbine High School massacre was memorialised, and threats were called in to other Denver-area schools.
The Columbine attack, in which two teenagers killed 13 people, marked the beginning of a new era in the United States - a time when the threat of school shootings has taught a generation of children how to flee, hide and even fight back when faced with a shooter.
The week of the anniversary, one of those threats shut down area schools for nearly half a million students when an 18-year-old Florida woman who authorities say was a threat to the community flew to Denver, purchased a weapon and seemingly disappeared.
After a two-day manhunt, Sol Pais was found dead. No one else was injured.
The anniversary came a few days later, and when it was over, the relief was palpable in the community, said John McDonald, head of security for the Jefferson County Public School District.
"But for the school safety community, we can never let our guard down," he said. "This is a reminder of why."
It had been only days since another school shooting. At the University of North Carolina at Charlotte last week, a student tackled a gunman who opened fire in a classroom, police said, killing two and wounding four others.
- Washington Post with AP