It was the second deadliest shooting in a US public school after the 2012 massacre of 20 first-graders and six educators at Sandy Hook Elementary in Newtown, Connecticut. The district will offer grief counseling to students and their families.
The suspect, 19-year-old Nikolas Cruz, was expelled for unspecified disciplinary reasons, Runcie said. He is due in court Thursday.
The shooting drew an outcry among Democratic lawmakers on Capitol Hill that it was time for additional gun control measures, such as a ban on assault rifles and expanded background checks, few of which are expected to get any traction in the GOP-controlled Congress.
The White House says President Donald Trump will address the nation about the Florida school shooting at 11 a.m. EST.
Broward County Mayor Beam Furr said during an interview with CNN that the shooter was getting treatment at a mental health clinic for a while, but that he hadn't been back to the clinic for more than a year.
Trump tweeted Thursday about the shooting at a Parkland, Florida, high school.
According to WTVJ, someone pulled the fire alarm at the high school before opening fire on students. But the school already had a fire drill earlier in the day, leading some to think it was a false alarm. Jim Gard, a math teacher who said Cruz had been in his class previous year, said he believes the school had sent out an email warning teachers that Cruz shouldn't be allowed on campus with a backpack. And yet, it didn't save enough. When he visited Las Vegas to mourn with the families of those victims, Trump called the shooter "demented" and a "very sick individual", though he added that "we'll be talking about gun laws as time goes by".
"We did everything that we were supposed to do". Broward County Schools has prepared us for this situation and still to have so many casualties, at least for me, it's very emotional.
Kardashian West said: "We owe it to our children and our teachers to keep them safe while at school".
In an evening press conference, Sheriff Scott Israel said 12 victims had been identified from the school, including an American football coach.
The former student who opened fire Wednesday with an AR-15 rifle was charged Thursday morning.
Freshman Kayden Hanafi said he heard two gunshots and saw people running out of another building on campus. As he and his classmates went into lockdown, many thought the noise might have been firecrackers. It was the nation's deadliest school shooting since a gunman attacked an elementary school in Newtown, Connecticut, more than five years ago. According to a law enforcement source, the suspect initially mixed in with the crowd of students to try to get away, but it didn't work.
Israel said that the shooting began outside of the school, and then Cruz allegedly moved inside of the school. Victims have been and continue to be transported to Broward Health Medical Center and Broward Health North hospital.
As news of the shooting spread, desperate parents gathered near the property, searching for their children at the nearby Walmart where the students and staff gathered after being evacuated.
The victims are a mix of students and adults, officials said. One died in the street and two died at the hospital, Israel said.