Sergio Caldera, a 17-year-old student at Apalachee High School, recalled the moment an active shooter tried to open the door to his classroom in a phone call with ABC.
The senior described his teacher running to the door during his chemistry class amid hearing screams from what he said sounded like the classroom next door at roughly 11:00 a.m.
Caldera then states that his teacher opened the door, but another school official quickly ran over, closed it, and locked the door. He and his classmates ran to the back of the classroom and huddled among each other. A moment later he said someone started pounding on the door, yelling, "Open the door, open the door" multiple times.
The knocking soon stopped before more gunshots rang out and he heard more screams.
He told the news outlet that he's pretty sure that it was the shooter who had tried opening the door.
Students were evacuated to the school's football stadium at roughly 11:30am, he added.
The Georgia high school was placed on lockdown Wednesday morning due to what authorities called an "active shooter situation."
One suspect was apprehended after the shooting and is currently in custody.
Four casualties and multiple injuries have been reported so far.
