BREAKING: 'Active shooter situation' at Fla. high school; Multiple casualties reported [photos, video]; Update: Suspect in custody; Sen. Bill Nelson says 'many deaths'; Update: Sheriff's office confirms at least 17 deaths

Breaking news out of Broward County, Florida, at Marjory Stoneman Douglas High School:

BREAKING: several students being treated after shooting at high school in Parkland, FL. @7News pic.twitter.com/lKhZZ8LYk1

— Alex DiPrato (@AlexDiPrato) February 14, 2018

BREAKING: Authorities are responding to reports of a shooting at a high school in Parkland, Florida. This is a developing story. https://t.co/0KpCmq0gMe pic.twitter.com/VQxuZ0iOdq

— CNN (@CNN) February 14, 2018

#UPDATE: Fire Rescue: At least 20 injured after shooting at Marjory Stoneman Douglas High School pic.twitter.com/uAXktQ8I0o

— WSVN 7 News (@wsvn) February 14, 2018

Sheriff: active shooter situation in Broward County, FL, at Marjory Stoneman Douglas High School — WSVN reports that rescue workers say at least 20 injured

— Jake Tapper (@jaketapper) February 14, 2018

"Again, they are asking those students, those faculty members, those staff members at Marjory Stoneman Douglas High School to stay barricaded inside the school, to not try to run out of there. Stay barricaded. Police are on their way. They are heavily armed." pic.twitter.com/Okivcylz4T

— CBS Evening News (@CBSEveningNews) February 14, 2018

"I am in touch with a student inside the school, in hiding in a tiny closet with a lot of classmates and their drama teacher," @CBSMiami anchor says of reported high school shooting in Florida. "They are all okay, but they are scared, as you can imagine." https://t.co/1Y5NBGZMdE pic.twitter.com/olpt0IndPh

— CBS News (@CBSNews) February 14, 2018

Students with hands up being brought out of school. Gunman still at large, preliminary reports up to 50 victims #breaking #CBSLA #StonemanShooting pic.twitter.com/RztdbcKLXs

— Sandra Mitchell (@CBSLAsandra) February 14, 2018

"This is a multi-casualty incident, according to law enforcement officials, but we do not know exactly what that means and how many people have been injured," @CBSMiami reports on shooting at Parkland, Florida, high school https://t.co/1Y5NBGZMdE pic.twitter.com/ppVBDVq8eU

— CBS News (@CBSNews) February 14, 2018

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Update:

JUST IN: More students run out of Marjory Stoneman Douglas High School in South Florida.

Tune in to @MSNBC for live breaking news coverage pic.twitter.com/EbwHe7SkSC

— MSNBC (@MSNBC) February 14, 2018

What a horrific scene. pic.twitter.com/80531BiQS7

— Evan McMurry (@evanmcmurry) February 14, 2018

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Update:

Student says alleged school shooter was a "troubled kid" pic.twitter.com/O0zZ6An2XM

— WSVN 7 News (@wsvn) February 14, 2018

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Update:

#Breaking "That's my baby sister." – Witness says he's spoken to his sister who is inside school where active shooter situation underway in Parkland, FL ~3000 students at the high school per @NBCNews pic.twitter.com/8rJnZcMW8t

— Jim Rosenfield (@jimrosenfield) February 14, 2018

#BREAKING: One of the students in Parkland high school #Florida shared photos of students texting their parents, hiding beneath chairs, during the shooting pic.twitter.com/lNQrLYisjY

— Amichai Stein (@AmichaiStein1) February 14, 2018

Awful.

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Update:

LIVE UPDATES: Suspect is now in custody according to city offiicals https://t.co/wRWxuObnTK pic.twitter.com/jocFl7r7gQ

— WHIO-TV (@whiotv) February 14, 2018

Person being put in the back of a patrol car matches description of shooter @WPLGLocal10 heard on scanner traffic. pic.twitter.com/eVSE62YDXo

— Ian Margol (@IanMargol) February 14, 2018

#BREAKING: Suspect is now in police custody after this afternoon's shooting at Marjory Stoneman Douglas High School in Parkland. pic.twitter.com/aOXF0yq4Ip

— Ryan Saavedra (@RealSaavedra) February 14, 2018

Shooter is now in custody. Scene is still active. #stonemanshooting

— Broward Sheriff (@browardsheriff) February 14, 2018

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Update:

Oh no:

Florida Sen. Bill Nelson told Fox News "there are many deaths" in the high school shooting in Parkland.

— Jason Leopold (@JasonLeopold) February 14, 2018

There are no words.

Horrific and heartbreaking ? https://t.co/31GAjwXYwQ

— WhigsnTwigs (@WhigsnTwigs) February 14, 2018

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Update:

Law enforcement sources confirm the name of the #Floridashooting suspect is Nicholas Cruz, a 20-year-old former student at Marjory Stoneman Douglas High School. #BreakingNews

— Mimi Whitefield (@HeraldMimi) February 14, 2018

So far we have at least 14 victims. Victims have been and continue to be transported to Broward Health Medical Center and Broward Health North hospital. #StonemanShooting

— Broward Sheriff (@browardsheriff) February 14, 2018

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Update:

#UPDATE In an interview, a student said: "everyone predicted this." >https://t.co/OkO5hke2za pic.twitter.com/ZyPFw0AcQL

— FOX5 Las Vegas (@FOX5Vegas) February 14, 2018

Uh oh https://t.co/WXRud3205j pic.twitter.com/mHJDXlC1Td

— Allahpundit (@allahpundit) February 14, 2018

Disturbing.

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Update:

BREAKING: At least 15 people are dead following shooting at Stoneman Douglas High School in Parkland, Florida, law enforcement officers on the scene tell @ABC News. https://t.co/KLCBY2b3mN pic.twitter.com/uW1n6WjWDu

— Nightline (@Nightline) February 14, 2018

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Update:

The sheriff is now confirming that at least 17 people have died:

17 are dead according to the sheriff. @7News

— Alex DiPrato (@AlexDiPrato) February 14, 2018

Now: Sheriff confirms "17 people died" in Parkland high school shooting.

— Ari Melber (@AriMelber) February 14, 2018

#BREAKING: 17 deaths from #StonemanShooting
12 in school Bldg
2 outside bldgs
1 en route to hospital
2 at hospital pic.twitter.com/RYF1caQy3A

— Heather Lacy (@Heather_Lacy1) February 14, 2018