Seventeen people have been killed in a shooting at a Florida high school on Valentine's Day, local police have confirmed.
- Suspect Nikolas Cruz is a 19-year-old former student
- 17 people are confirmed dead and several are in surgery
- Stoneman Douglas High School is one of the biggest schools in Florida
Suspect Nikolas Cruz, 19, is a former student of Marjory Stoneman Douglas High School, about 72 kilometres north of Miami.
Broward County Sheriff Scott Israel said Mr Cruz was taken into custody without incident.
"He got expelled for disciplinary reasons, I don't know the specifics," he said.
"We are beginning to dissect his websites and things on social media that he was on and some of the things that have come to light are very, very disturbing.
"I don't know anything about the firearm. He had countless magazines, multiple magazines and at this point we believe he had one AR rifle, I don't know if he had a second one."
Sheriff Israel said of those people killed, 12 were inside the building, two were outside the school and one person was on the road.
Sixteen people were taken to hospital but two of them died from their injuries. At least three people remain in a critical condition.
Sheriff Israel said one of the victims who died was a football coach while a deputy sheriff's son had been shot in the arm, but was being treated at a local hospital for non-life threatening injuries.
Shooter 'set off the fire alarm'
Florida Senator Bill Nelson told CNN he had been briefed by the FBI that the shooter wore a gas mask and had smoke grenades, but did not know if he had used the grenades.
"[He] set off the fire alarm so the kids would come pouring out of the classrooms into the hall. And there the carnage began," Mr Nelson said.
Teacher Melissa Falkowski said her class was evacuating for what they thought was a fire drill.
"We got maybe 15, 20 steps out of the classroom and we were told that we were 'Code Red'," Ms Falkowski told CNN.
"We ran back inside and crouched down on the floor … there were kids in the closet."
Ms Falkowski said her friend who was teaching in the freshman building, where the shooting reportedly happened, said she saw three bodies on the floor as she was leaving.
She said the teachers had been trained on how to deal with a shooting just six weeks ago.
"If we hadn't had that training, it could have been a lot worse," she said.
"In fact, a lot of us probably thought this was the drill that we were supposed to have this semester to practice. And it wasn't, it was the real thing."
'Have you heard from your child yet?'
McKenzie Hartley told Hack her 17-year-old sister was forced to hide in a closet for more than two hours while the gunman entered the school and shot her classmates.
"I found out almost immediately because my sister's friend was in one of the first classrooms that unfortunately got shot up," Ms Hartley said.
"Her friend texted her almost immediately saying 'get out of the way, hide — there's someone in the school with a gun'.
"My sister sent me and my mum a text immediately saying, 'Oh my God there's a shooter on campus'.
"Unfortunately she never got evacuated because they suspected he might have been in that building, so she spent two-and-a-half hours just hiding in a closet with her whole class."
Len Murray's 17-year-old son, a junior at the school, sent his parents a chilling text message.
"Mom and Dad, there have been shots fired on campus at school. There are police sirens outside. I'm in the auditorium and the doors are locked."
Those words came at 2:30pm. A few minutes later, he texted again saying: "I'm fine."
Mr Murray raced to the school only to be stopped by authorities under a highway overpass within view of the school buildings in Parkland.
No information was immediately given to parents, Mr Murray said.
"I'm scared for the other parents here. You can see the concern in everybody's faces."
"Everybody is asking, 'Have you heard from your child yet?'"
Aerial footage showed police in camouflage with weapons drawn entering the school.
Dozens of students could be seen frantically running and others quickly walking out as emergency workers treated those who were injured.
Some students exited buildings in single-file rows with hands raised overhead to show they carried no weapons.