The young man who the authorities identified as the shooter, Mr. Cruz, previously attended Marjory Stoneman Douglas but was expelled after getting into trouble.
Dr. Evan Boyer, the medical director at Broward Health North's Department of Emergency Medicine, told reporters that the suspect was among 17 patients taken to local hospitals after the shooting.
Former student Andrew Hofmann said Feis, who had worked as a security guard at the school for more than eight years, was "very well dedicated to the safety of the school", The Miami Herald reported.
A teenage suspect is in custody after a shooting spree at a secondary school in the USA state of Florida resulted in "numerous fatalities".
Law enforcement sources said the suspect used a.223 caliber, AR-15 style firearm in the shooting.
ABC News is reporting that Cruz fled after the shooting, blending in as students evacuated the building.
A SWAT team has been filmed storming a U.S. classroom where terrified students huddled in fear of a gunman who killed at least 17 people and injured dozens more.
"I don't want to come back to this school", she said.
US President Donald Trump tweeted: "My prayers and condolences to the families of the victims of the bad Florida shooting".
"We routinely run drills or institution to be ready for instances like this so we have a process in place that gets initiated, so there's calm, collected care that our patients receive", Dr. Boyar said.
Police and ambulances surrounded the school with many of those iinjured treated on stretchers at the scene.
In the late press conference, Florida Governor Rick Scott, a Republican, said it was an act of "pure evil" but refused to discuss gun controls. "I don't know how we're alive", says student Gabrielle Pupo.
According to Fox News' Trace Gallagher, the suspects' social media showed that he was "fascinated by guns".