(Update) LIVE Video- Suspect in deadly Florida school shooting in custody. Marjory Stoneman Douglas High

Freshman Kayden Hanafi said he heard two gunshots and saw people running out of another building on campus. Initially, most people though the sounds were firecrackers. Then, he and others went to lockdown in a classroom.

“It’s really a blessing to still be alive,” he said.

Aerial footage from WSVN showed a number of people lying on the ground outside the school, being treated for injuries and moved to ambulances. As students streamed away from the school, some ran while others walked quickly in orderly lines with their hands on or above their heads.

Nicole Baltzer, 18, said she was in trigonometry class about 10 minutes before the end of the school day when the fire alarm went off. As students evacuated, she heard six gunshots and everyone started running back inside the school, Baltzer told

CNN’s Sara Ganim.

“I heard so many gunshots, at least like six. They were very close,” Baltzer said.

Baltzer said she is still on lockdown in a classroom on the second floor. Her stepsister is also on lockdown in a different classroom, she said. “Everyone just started freaking out,” a student told CNN affiliate WSVN.”We all thought it was a fire drill because we had one previously today,” he said. “And we thought it was, so no one was that nervous, but then word started going around that it was shots and not just, like, something else, everyone just started running towards the canal.”