The Valentine’s Day bloodshed is the latest outbreak of gun violence that has become a regular occurrence at schools and college campuses across the United States over the past several years.
It was the 18th shooting in a U.S. school so far this year, according to gun control group Everytown for Gun Safety. That tally includes suicides and incidents when no one was injured, as well as the January shooting in which a 15-year-old gunman killed two fellow students at a Benton, Kentucky, high school.
Here is what we know about the incident in Florida so far:
The assailant began firing at Marjory Stoneman Douglas High School toward the end of the school day, spraying bullets both inside and outside the school and sending classrooms into lockdown.
Authorities apprehended the suspected shooter off of the school’s campus and took him into a custody about an hour after the incident.
The large high school is in the city of Parkland, about an hour north of Miami.
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How many people died?
As of now, sheriff’s officials have identified 17 victims. That number could rise as more information continues to come in.
Of those victims, five died outside of the school and 12 were shot inside the building.
What weapons were used?
The assailant was wielding an AR-15, a semiautomatic rifle that has been used in other mass shootings, and had “multiple magazines,” Mr Israel said.
Is there a suspect?
Broward County Sheriff Scott Israel has identified the suspect as 19-year-old Nikolas Cruz, a former Marjory Stoneman Douglas High School student who had been expelled for disciplinary reasons.
Investigators are already piecing together information about Mr Cruz, and Mr Israel said they have quickly turned their focus to Mr Cruz’s online footprint.
Some of the content they have found is “very disturbing”, Mr Israel said.
The teenager is in custody.
What has been the reaction?
Donald Trump weighed in on Twitter by saying his “prayers and condolences” were with the families of the victims, adding that “No child, teacher or anyone else should ever feel unsafe in an American school”. He said he had spoken to Florida Gov Rick Scott.
Other elected officials called the shooting the latest evidence that America must pass new laws to try and stem periodic mass gun violence.
Senator Bernie Sanders said that after numerous school shootings since the start of 2018, “Congress might want to consider common-sense gun safety legislation and save innocent lives”.
Connecticut Democrat Chris Murphy said on the Senate floor that “this happens nowhere else other than the United States of America”, which he called “a consequence of our inaction”.