Six-year-old John Oliver Zippay — or "JO," as his family and friends call him — received a hero's welcome back at school after he finished chemotherapy treatments for Leukemia.

JO was three when he was diagnosed with Leukemia on Halloween 2017, after his parents noticed a bruise that wasn't healing.

"It was a typical day," his mom, Megan Zippay, tells ABC News. "He went to school, we went home, he got dressed for trick-or-treating. Then we got a call at four in the morning."

The call was the hospital with the results of his tests: He had Leukemia. John Oliver's father, John Zippay, recalls that their entire world "just stopped" — the news "was a huge shock" to them.

After years battling the disease, JO has completed chemotherapy, and not only are his parents proud of him, but his classmates are, too. One in particular came up with the idea shown in the video above — to welcome JO back to school with a standing ovation.

"She wanted to do a little celebration [when he returned to school after finishing his chemotherapy treatments]," mom Megan says.

"JO asked us, 'Maybe they’re going to do an announcement that I’m all done with chemo?'" John says. Instead, the little boy's classmates from several classes and grades lined up in the hallway to cheer for JO. He was overjoyed.

"I think him coming down the hall and everyone applauding him was a good end," Megan continues. His reaction to the surprise welcome back "was pure happiness."

After three years of daily chemotherapy and countless doctor appointments with monthly steroids, the family is thrilled that he is done with the intense regimen and fight.

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