Seventeen people have been killed in a school shooting in Florida Wednesday afternoon, Broward County Sheriff Scott Israel said.

The suspected shooter has been identified as Nikolas Cruz, 19, a former student at the school who was suspended for disciplinary reasons, the sheriff said. He was taken into custody near Marjory Stoneman Douglas High School in Parkland, Fla. after the shooting.

Cruz had at least one rifle and multiple magazines when he opened fired inside the school.

Shooter is now in custody. Scene is still active. #stonemanshooting — Broward Sheriff (@browardsheriff) February 14, 2018

The Broward Sheriff's Office says they responded to the school after reports of gunfire.

Today, close to Marjory Stoneman Douglas High School’s dismissal, students and staff heard what sounded like gunfire. The school immediately went on lockdown but is now dismissing students. We are receiving reports of possible multiple injuries. Law enforcement is on site. — Broward Schools (@browardschools) February 14, 2018

RELATED: Map of 18 U.S. school shootings so far in 2018

Coral Springs Police said on their Twitter account Wednesday that the school was locked down and that students and teachers inside were told to remain barricaded until police reached them.

My prayers and condolences to the families of the victims of the terrible Florida shooting. No child, teacher or anyone else should ever feel unsafe in an American school. — Donald J. Trump (@realDonaldTrump) February 14, 2018

TV footage showed at least one person being wheeled to an ambulance on a gurney while emergency workers appeared to be helping others on the sidewalk. The news broadcasts also showed students running across the street.

Most of the fatalities were inside the building but some students were found fatally shot outside.

Michael Simon, with Arizona Security Group, suggests the following if you're in an active shooter situation:

Turn off the lights - Being in a dark room could deter the shooter.

- Being in a dark room could deter the shooter. Get behind a wall - Try to block yourself from being seen by the shooter.

- Try to block yourself from being seen by the shooter. Lock the door - If your door doesn't lock, put something in front of the door to block the shooter from entering (i.e. a table, a desk, a filing cabinet)

- If your door doesn't lock, put something in front of the door to block the shooter from entering (i.e. a table, a desk, a filing cabinet) Cover windows - Put something up against all windows to block the shooter from seeing inside.

Since 2014, Arizona Security Group has helped dozens of schools, churches, and businesses across the Valley. In just four years, Simon says demand has doubled.