The Margate Fire Rescue Team described the shooting as a “mass casualty incident” which reportedly means that at least 20 people were injured.
The shooter was at large until 4 p.m., when he was reportedly arrested.
Authorities said that students and teachers should remain barricaded in classrooms until they are reached by police.
A person who claims to be inside the high school tweeted a picture from inside a classroom where students can be seen sitting under their desks.
President Donald Trump tweeted a message of grief and support shortly after receiving the news.
“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,” Trump wrote. “Just spoke to Governor Rick Scott. We are working closely with law enforcement on the terrible Florida school shooting.”
The FBI is in touch with local law enforcement and is responding to the attack, Fox News reported.
A student told WSVN that he knows the shooter.
“He’s been a troubled kid, and he’s always had a certain amount of issues going on,“ the student said. ”He shot guns because he felt it gave him, I guess, an exhilarating feeling.”
“I stayed clear of him most of the time. My time in alternate school, I did not want to be with him at all because I didn’t want to cause any conflict with him because of the impression he gave off,” the student added.
Police identified a student as a person of interest but have not released a name.
WSVN reports seeing at least one person on a stretcher being carried to an ambulance and four more people being tended to by rescue personnel.
CBS shared a video of police arresting a suspect. It is not clear if the person in the video is the same as the gunman.
The Broward County sheriff said that the scene is still active, BBC reported.