Just before wrapping up his final class of the day, 15-year-old Michael Katz said he heard a loud bang at 2:20 p.m. from what he initially thought was a garbage truck.
"It was really loud. Then I heard it again," Michael, a student at Stoneman Douglass High School in Parkland, Florida, told ABC News. "Then I heard frantic screaming. I've never heard such loud screams in my life. Then we realized there was a shooting at my school."
He said his English teacher, Ms. Lyons, already had the classroom door locked, and was signaling with her hands for everyone to get down on the ground and stay silent. He said he heard a barrage of gunshots coming in such a rapid succession he couldn't count them all.
"Then I head more and more shots, and I heard banging next door," Michael said. "My first instinct was to text my mom and dad and tell them that I loved them in case I was killed. Then I called 911. I just said there's an active shooter at Stoneman Douglass and hung up because I heard footsteps coming back toward our classroom."
He said several of the roughly 20 students in the class started to cry and other student were trying to calm them down, telling them that everything was going to be fine.
Michael said that after about four or five minutes, the gunfire subsided. He said he heard the sound of police yelling in the halls and banging on his door.
"My teacher didn't want to open the door at first, then we heard them say, 'Police, open up!'" he said.
When the door flung open officers were swarming the hallway, he said. He said he and his classmates formed a single line, put their hands in the air and filed out.
"We moved in a single line, then lying around the wall from my room there were two dead bodies on the ground," he said. "There was a boy and a girl. They were both extremely pale and bleeding."
As he made his way to the exit, he said, "I saw one student walking with blood on his face. There was blood and glass all over the floor."
Once outside, he said, he and his classmates sprinted across the street with their hands still in the air.
He said his father, a former police officer, was waiting for him outside the school.
"I heard my dad say, 'Look over here,' and I just sprinted to the car and jumped in," Michael said.
Michael said the thought of dying crossed his mind as he was sitting under his desk in the classroom.
"I feel total shock, confusion," Michael said from the safety of his home. "I've never been more scared in my life."
Broward County School Superintendent Robert Runcie said there were "numerous fatalities" and the Broward County Sheriff's Department said at least 14 victims were transported to local hospitals.
Another student, Alexandra Robinson, told ABC News from her home that she was confused when she heard the fire alarm because they had already practiced a drill this morning. The principal voice then came over the intercom and ordered students to evacuate.
Alexandra said she thought it was a fire until she heard “two pops,” but she wasn’t able to gauge how close they were to her. She and two of her friends then ran “for their lives.”
At one point, they stopped running, and a security guard instructed them to keep going.
“That’s when I knew this was, like, a real shooting thing,” Alexandra said.
She and her two friends ran to a Walmart store near their school, which took about 10 minutes – five to get off of the sprawling campus, and another five to reach the store.