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HIGHLANDS RANCH, Colo. (KDVR) — Thursday marks one year since the tragic school shooting at STEM School Highlands Ranch. Kendrick Castillo, 18, was a senior at the school and was killed in the shooting.

On Thursday morning, Kendrick’s father, John Castillo, sent out a tweet.

“Up and ready for one of the most difficult days of my life. Reliving our worst nightmare on May 7th when we found out Kendrick was murdered while saving other classmates.” John said.

There will be a prayer service held on Thursday at 2 p.m. on the “In Honor of a Hero: Kendrick Castillo” Facebook page.

Castillo was credited with helping saving the lives of his classmates during the shooting.

“Kendrick lunged at [the suspect], 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,” senior Nui Giasolli said in an interview Wednesday morning with NBC News.

Giasolli said it began when one of the suspects arrived late to class.

“The next thing I know, he is pulling a gun and is telling nobody to move,” he said.

Castillo’s parents said his heroic actions were unsurprising.

“We’re not surprised because that was in his makeup. You know, Kendrick was a giving kid. He would do something to save his friends if he knew he had to do it,” said his father, John Castillo.

The parents said Kendrick’s quick thinking prevented more deaths.

“If he didn’t do it, what would this mess look like?” John Castillo said. “He gave up his life for others.”

Kendrick’s parents said they were told their son probably did not suffer, as his death was likely instant.

They said Kendrick planned to attend Arapahoe Community College.

“Life’s not fair, it’s dangerous.” John Castillo said. “My son paid the ultimate price.”

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