At least 17 people have been killed in a mass shooting at a high school in Parkland, Florida, police say.
The suspect has been named as Nikolaus Cruz, 19, and is a former student at the school who had been expelled.
Cruz, who was armed with “multiple magazines”, began the shooting spree outside the school before opening fire inside, according to officials.
Students were forced to hide in classrooms as police scoured the building.
Broward County Sheriff Scott Israel told reporters that Cruz had used a rifle and opened fire outside the school where three people were killed. He then entered the building and killed 12 people.
Two people later died after being taken to hospital.
Dr Evan Boyar of Broward Health told reporters late on Wednesday that 17 people had been taken to area hospitals.
He added Cruz was among those treated and was released into police custody. Three people remained in a critical condition and three others were in stable condition, he said.
How it unfolded
Earlier on Wednesday, the local public school district tweeted: “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.”
Police were clearing students from the school “one building at a time”, the school said.
Video footage from the scene showed students being evacuated in small groups, while armed police patrolled the school’s perimeter.
As the situation unfolded, helicopter footage appeared to show a person being handcuffed and placed in the back of a police car.
Coral Springs Police department tweeted instructions to teachers and students to “remain barricaded inside until police reach you”.
US television networks reported large numbers of parents had gathered outside the police perimeter.
Several witnesses inside the building at the time told news outlets that the fire alarm had been set off as the shooting began.
One student evacuated from the school told CBS that Miami students had thought it was a drill.
“We already had one earlier this morning… and then we heard gunshots; some students thought it was not that serious.”
Another student, Bailey Vosberg, said: “I heard what sounded like fireworks and I looked at my friend and he asked me if I heard that.”
“Immediately, I knew. I didn’t say anything to him, I just hopped over the fence and I went straight to the road that our school is located on – and as I got there there was just Swat cars and police units, police vehicles just flying by, helicopters over the top of us.”
A teacher told WSVN that she hid in a closet with 19 students for 40 minutes – and that the school had undergone training for such a situation six weeks ago.
Reaction to the shooting
President Donald Trump tweeted condolences “to the families of the victims”. White House Deputy Press Secretary Lindsay Walters said the president had been briefed and that the White House was monitoring the situation.
Florida Governor Rick Scott said he spoke to President Trump about the shooting, and was continuing to receive updates from law enforcement.
Congressman Ted Deutch, the district’s representative, tweeted: “I’m sick about this news from home. Just spoke with the sheriff. This is devastating.”
He said it was an “incredible school in my district – great teachers and staff, involved parents and amazing kids. Spoke with the kids there just a few weeks back.”
Students were taken by bus to a “staging area” on Heron Bay Blvd, Coral Springs, where their parents could collect them.
Wednesday’s attack is the 18th shooting in the US this year on or around school premises, according to research by Everytown for Gun Safety.
Since 2013, there have been 291 reported school shootings in America, which averages out to about one per week.
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