At the time McNair Discovery Learning Academy was full of children and their teachers.
Police later identified the gunman as Michael Hill, who they said walked into the elementary school armed with an AK-47 and hundreds of rounds of ammunition.
Police arrested Hill 24 minutes after Tuff called 911.
McCray told Byfield she finally felt like she could breathe when police stormed into the building and arrested Hill.
"I was extremely emotional after all of this was said and done," McCray said. "I was like thank you lord so much for answering prayers. I had to give my honor to God because I know that this situation was in his hands from the time the call clicked in my ear."