The heroic Oklahoma principal who tackled a gunman that had entered the school said "there was no denying what it was" when gunshots were fired inside the school last month.

"It was a typical day until the gunshot outside of my office," Pauls Valley High School principal Kirk Moore exclusively told CBS News while reflecting on the terrifying incident.

The 60-year-old recalled rushing toward the gunman, later identified as 20-year-old former student Victor Hawkins, and said his actions were "just instinct."

"In 37 years, you go through trainings and drills and what you should do. That all goes out the window," Moore said. "I'm glad it worked out the way it did again. I think God's hand was on all of us, but I can't explain why it happened the way it did."

Moore said he didn't initially know he was shot during the school shooting.

"We fell on the padded bench area, and he (Hawkins) just started emptying the gun into the floor," Moore said. "Once I got stood up, I felt the … warmth of the blood and then, I knew I'd been hit."

But because of his actions, no other students or faculty were hurt.

"I can't explain why I did what I did," he said. "I think many, many people would have done the same thing. They just don't realize it."

Outpouring of support

Moore was comforted by familiar faces of first responders who cared for him. 

"My MediFlight nurse, all of the firemen, police officers – former students. And it's so comforting seeing those faces rather than strangers," he said.

The longtime educator has received an outpouring of support, including thank you letters from around the world.

A family who lost a child in a school shooting wrote a letter to Moore, saying, "We are writing to honor your extraordinary valor when violence threatened the lives of those entrusted to your care, you did not hesitate. In doing so, you spare countless mothers and fathers the lifelong agony that we now endure."

A few weeks ago, the students at Pauls Valley High School honored Moore, crowning him this year's prom king.

Over the past month, more than $20,000 has been donated to a GoFundMe page for Moore, but he redirected the money to the "Principal Kirk Moore Fund" at the high school, which supports graduates.

In addition, the companies Love's Travel Stops & Country Stores, OERB, The People of Oklahoma Oil and Natural Gas, and Hobby Lobby are donating a total of $50,000 to the "Principal Kirk Moore Fund" at Pauls Valley High School.

"That's awesome," Moore said, reacting to the donation. "It's gonna be money that will be a graduation gift for kids that stuck it out. It's gonna be a nice graduation gift that you did it and reward them for that."

Suspect faces multiple charges

Hawkins was arrested at the school and is now facing multiple charges, including shooting with intent to kill. 

"I never had Victor in my office for any disciplinary reasons," Moore said and added he thinks of Hawkins often.

"I feel like we need to pray for that kid as much as we pray for anybody," Moore said. "I think he was just in a bad spot at that time."

Hawkins has pleaded not guilty and remains in custody on $1 million bond.