A 19-year-old gunman returned to a Florida high school where he had once been expelled for disciplinary reasons and opened fire with an assault-style rifle on Wednesday, killing 17 people and injuring more than a dozen others before he was arrested, authorities said.
The violence erupted shortly before dismissal at Marjory Stoneman Douglas High School in Parkland, a placid, middle-class community about 72 kilometers (45 miles) north of Miami. Television footage showed students streaming out of the building, many with hands raised in the air, as dozens of police and emergency services personnel swarmed the area.
The gunman was identified as Nikolas Cruz, who previously attended the school and was expelled for unspecified disciplinary reasons, Broward County Sheriff Scott Israel said at a news briefing hours later.
As a high school freshman, Cruz was part of the U.S. military-sponsored Junior Reserve Officers' Training Corp program at the school, according to Jillian Davis, 19, a recent graduate and former fellow JROTC member at Stoneman Douglas High.
In an interview with Reuters outside the school, she recalled his "strange talking sometimes about knives and guns," adding, "no one ever took him seriously."
Chad Williams, 18, a senior at Stoneman Douglas, described Cruz as "kind of an outcast" who was known for unruly behavior at school and was "crazy about guns."
The gunman surrendered to police without a struggle, Israel said. He was armed with an AR-15-style rifle and had multiple magazines of ammunition.
"It's catastrophic," Israel said. "There really are no words."
"It's a horrific situation," Broward County Schools Superintendent Robert Runcie told reporters separately.
U.S. Senator Bill Nelson of Florida told CNN the gunman wore a gas mask, was carrying smoke grenades and set off a fire alarm, prompting students to pour out of their classrooms into the hallways. "There the carnage began," Nelson said.
Twelve of the dead were killed inside the school, two others just outside, one more on the street and two other victims died of their injuries at a hospital, Israel said. He said the victims comprised a mixture of students and adults.
Authorities at two nearby hospitals said they were treating 13 survivors for bullet wounds and other injuries, five of whom were listed in critical condition.
The Valentine's Day bloodshed in the Miami suburb of gated communities with palm- and shrub-lined streets was 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.
Scenes of fear
Staff and students told local media that a fire alarm went off around the time the shooting started, sparking chaos as some 3,300 students at the school first headed into hallways before teachers herded them back into classrooms, to seek shelter in closets.
Kyle Yeoward, a 16-year-old junior, told Reuters he was in the bathroom on the second floor of a building when he heard two shots.
"He let loose on the freshman building," Yeoward said.
CBS News posted a brief clip of cell phone video footage the network said was taken from inside a classroom, showing what appeared to be several students. A rapid series of loud gunshots are heard amid hysterical screaming and someone yelling, “Oh my God.”
McKenzie Hartley, 19, who identified herself as the sister of a student at the school described the scene in a text message to Reuters: "She heard him shooting through the windows of classrooms and two students were shot."
Anguished parents checked on their children.
"It is just absolutely horrifying. I can't believe this is happening," Lissette Rozenblat, whose daughter goes to the school, told CNN. Her daughter called her to say she was safe but the student also told her mother she heard the cries of a person who was shot.
Televised images showed dozens of students, their arms in the air, weaving their way between law enforcement officers with heavy weapons and helmets, and large numbers of emergency vehicles including police cars, ambulances and fire trucks.
The school had recently held a meeting to discuss what to do in such an attack, Ryan Gott, a 15-year-old freshman told CNN.
"My prayers and condolences to the families of the victims of the terrible Florida shooting," U.S. President Donald Trump said on Twitter. "No child, teacher or anyone else should ever feel unsafe in an American school."