What We Know So Far about the Florida High School Shooting17 people including students and adults were killed when a gunman pulled a fire alarm and then opened fire at Marjory Stoneman Douglas High School, about an hour northwest of Miami. Fifteen people were wounded.

The gunman has been identified as 19-year old Nikolas Cruz, a former student who was expelled from the school for disciplinary reasons

Cruz washeavily armed and was believed to be carrying an AR-15 rifle and "countless magazines," as well as smoke grenades and a gas mask. 

The shooter has beencharged with 17 counts of premeditated murder and is expected in court this afternoon. 

The Miami Herald reports Cruz was a "troubled teen with few friends and an obsessive interest in weapons. Administrators considered him enough of a potential threat that one teacher said a warning was emailed last year against allowing him on the campus with a backpack."

Two tips about Cruz had beenpassed along to the FBI, but they were never passed on to local law enforcement. 

The shooting is the deadliest on a school campus since the Sandy Hook massacre in Newtown, Connecticut, in December 2012.

Cruz and his biological brother were adopted by a family after their mother and her husband passed away. The two boys later moved in with a family friend. The adoptive family's attorney,James Lewis, says the family had "no idea, no predilection….they had no clue that this kid was dangerous." 

The shooter's family allowed him to have a gun butestablished rules around it, including that it had to remain locked up.

Meanwhile, Broward's sheriff is responding toseveral copycat threatsthat were called in to South Florida schools today. 

Information about some of the victims—including their heroic actions—has begun to emerge, and officials say a full list of the victims and a shooting timeline will be released today. 

The Associated Press reports that a white nationalist group has confirmed Cruz is a member. "The leader of a white nationalist militia called the Republic of Florida said Cruz was a member of his group and participated in exercises in Tallahassee," according to the article. ​

Security Management ​will continue to update this article as new information emerges.​

ASIS International Launching Active Assailant Program

12:15 p.m. ET Thursday

In the coming days, ASIS International will roll out a content program around the active assailant topic. The series will include expert input on how to prepare for, mitigate, and respond to these attacks. An upcoming article in Security Management will explore how unarmed guards can play a crucial role in defending against active assailants. The March Security Management podcast will feature interviews with members from the ASIS School Safety and Security Council. Upcoming "Ask the Expert" webinar series will further discuss the topic, as well as an upcoming classroom program. ​Click here for a current list of ASIS resources on active assailant​.

​trump addresses nation, says school safety is 'Top priority'

12:10 p.m ET Thursday

U.S. President Donald Trump addressed the nation this morning in the wake of a mass shooting at a Florida high school that left 17 dead and 14 injured. 

“No child, no teacher, should ever be in danger at an American school,” Trump said in his remarks on the shooting at Marjory Stoneman Douglas High School in Parkland, Florida. “No parent should ever have to fear for their sons and daughters when they kiss them goodbye. Each person who was stolen from us yesterday had a life ahead of them, a life filled with wonders and beauty, potential and promise.”

The gunman allegedly responsible for the shooting has been identified as Nikolas Cruz, a 19-year-old student who’d been expelled from the school, according to The New York Times. Cruz was enrolled at another Broward County school at the time of the shooting, and authorities told the Times they’d already discovered material on his social media accounts that was “very, very disturbing.”

Trump said that he has been in contact with Florida Governor Rick Scott, as well as the Florida attorney general and Broward County sheriff. He plans on visiting Parkland, Florida, to meet with families and local officials, but did not say when this visit would occur.

Trump also said that his administration is working closely with local authorities to investigate the shooting and “learn everything we can” about the incident. He then plans to work with state and local leaders to tackle the issue of mental health and school security.

Making schools safer is “our top priority,” Trump said, adding that it’s not enough to take actions “that make us feel like we’re making a difference—we need to make a difference.”

Trump’s comments on mental health, however, contradicted earlier actions that his administration has taken in regard to individuals with mental illness and firearms. Shortly after taking office in February 2017, Trump signed a bill into law that rolled back previous regulations that made it more difficult for individuals with mental illnesses to purchase guns.

“The rule, which was finalized in December 2016, added people receiving Social Security checks for mental illnesses and people deemed unfit to handle their own financial affairs to the national background check database,” NBC News reports.​Multiple Fatalities Reported at South Florida High School Shooting

5 p.m. ET Wednesday

Numerous people are dead and injured after a mass shooting at a south Florida high school Wednesday, officials said. The Broward County Sheriff's Office said there are at least 14 victims but did not say how many of those were injured or killed, USA Today reports.

The gunman was taken into custody nearly two hours after the shooting was reported, authorities said.

The shooting happened about 2 p.m. at Marjory Stoneman Douglas High School in Parkland, Florida, which is about 30 miles northwest of Fort Lauderdale, according to the Coral Springs Police Department.

Broward County Public Schools Superintendent Robert Runcie said "multiple fatalities" have been reported. "It's a horrific situation. It's just a horrible day for us," he said. "...This is a day we prayed would never happen in our county."

Runcie said every high school in the county has a police presence, adding there are typically two officers at every school. Margate Fire Chief Dan Booker told the Miami Herald that the shooting was a mass casualty incident. He said more than 20 were hurt, although he could not confirm exactly how many have been injured or how many were shot.

The school district released a statement explaining the shooting happened close to dismissal time. When students heard what sounded like gunfire, the school was placed on lockdown. ​