A former student who had been expelled for disciplinary reasons opened fire at a South Florida high school Wednesday, killing 17 people and wounding at least a dozen others, authorities said.
The suspected gunman, Nikolas Cruz, 19, was quickly arrested "without incident" after the shooting at Marjory Stoneman Douglas High School in Parkland, Broward County Sheriff Scott Israel said. Cruz had made "disturbing" posts on social media before the attack, Israel said.
Cruz was armed with at least one AR-15 semiautomatic rifle and "countless magazines," said Israel, who did not suggest a possible motive. Officials think he acted alone.
"This has been a day we've seen the worst of humanity," said Broward County Public Schools Supt. Robert Runcie.
Florida Gov. Rick Scott said the investigation would attempt to determine how a former high school student came to be armed with such a powerful weapon. "You come to the conclusion that this is just absolutely pure evil," he said.
Several students reported first hearing gunshots after someone pulled a fire alarm shortly before the end of school. Initially, they were confused. The school had held a fire drill earlier in the day.
Students were walking out of math teacher Jim Gard's classroom when a "code red" was announced over the school intercom — a warning about an active shooter. Most of Gard's students had already left, and he was only able to get six of them back into the classroom. He turned off the lights and locked the door.
Then, he said, "We heard all the popping noises."
Sen. Bill Nelson (D-Fla.) told MSNBC that Cruz wore a gas mask and brought smoke grenades with him. Cruz set off the fire alarm "so the kids would come out into the hallways, and thus he had the opportunity with a crowded hallway to start picking off people," Nelson said.
Cruz initially escaped by folding into the crowd, Broward County authorities said in a news release. "Responding deputies were met with hundreds of students fleeing the school. Investigators later learned that the shooter had concealed himself in the crowd and was among those running out of the school," it said.
Fifteen victims died at the school and two others died at a hospital, police said.
Cruz was taken to a hospital as a "precaution" after exhibiting "labored breathing" when he was taken into custody in a neighborhood in nearby Coral Springs, authorities said.
Hannah Siren, 14, was in math class on the third floor of the freshman building, where at least part of the shooting happened.
"The people next door to us must have not locked their door," said Hannah, breaking into tears. "They all got shot" — seven to 10 victims, she said.
Samuel Dykes, a freshman, added that he heard gunshots and saw several bodies in a classroom on the third floor.
Another student told WSVN-TV that when she ran into a classroom on the third floor to hide, a geography teacher opened the door to let her in, and when he started closing it, the teacher "was shot and killed right there," she said. "The door was open, [the gunman] could have walked in at any time." The students hid in the corner and survived.
"He kind of shielded them," one of his students, Christina Vega, told the television station. "He actually stepped up."
Christina added: "I don't want to go back to this school. I can't go up the stairs. There's blood on the stairs."
Throughout the school, students barricaded themselves inside classrooms and closets. In one classroom video that went viral on social media, students cowered beneath desks, sobbing and screaming as repeated gunshots can be heard nearby.
"Oh, my God! Oh, my God!" a student cried out.
Jude Lenamon, 15, was in his ninth-grade English class reviewing a chapter of "To Kill a Mockingbird" when the fire alarm went off. "At first we thought it was a fire," he said.
The class followed the teacher outside to a football field, where hundreds of students had gathered. They heard five or six shots.
"Doesn't that sound like gunshots?" Jude asked his teacher.
"Yeah, maybe," the teacher answered.
Jude's friends started crying. The crowd was ushered toward a fence. Each of the hundreds of students needed to go through a small gap in the fence to get to a parking lot, and a huge backup developed. Police were arriving and helicopters hovering.
"Everybody started panicking and trying to get out," Jude said. Many of the students started hopping the fence rather than wait in line. He recalled telling a friend, "It's going to be OK. Stay calm."
"People were definitely scared," he said.
Freshman Aidan Minoff live-tweeted the shooting from inside the classroom where he was hunkered down with others. "My school is being shot up and I am locked inside. I'm … scared right now," he wrote.
Another student posted a disturbing video of the shooting, capturing the thunder of the gunfire and the screams of students scrambling for cover.
Law enforcement personnel and ambulances swarmed to the school. Some students evacuated by walking in a chain with their hands on the shoulders of the students in front of them.
Emergency workers appeared to be treating victims for injuries on sidewalks outside the school. Parents gathered at the perimeter, some of them Christians with ash on their foreheads for Ash Wednesday, some wearing hearts to mark Valentine's Day.
Victims were taken to Broward Health Medical Center and Broward Health North hospital. By nightfall, officials had identified 12 of the 17 victims, and Florida Atty. Gen. Pam Bondi promised the state would pay for each of the victims' funerals.
The task of identification was made difficult by students who were killed without their backpacks or cellphones, officials said.
Helicopter footage from WSVN-TV showed police detaining a suspect with short hair and a dark red shirt and dark pants. The person was handcuffed and put in the back of a police car without apparent struggle.
Other students spoke to WSVN-TV after fleeing the campus.
"Three shots happened, and then everyone started freaking out," said one student, who identified himself as Sebastian. "We all thought it was a fire drill.... No one was that nervous, but when word started going around that it was shots … everybody started running."
Another student who declined to give her name reported hearing "five pops" after someone pulled a fire alarm.
"Kids were freaking out. Some kids froze; some were on their phones. Some were trying to Snapchat because they thought it was a joke, and it wasn't," she said.
One student claimed to have met the gunman at an off-campus learning center after getting kicked out of school.
"He's been a troubled kid, and he's always had a certain amount of issues going on," the student told WSVN-TV, saying the suspect previously had shown him pictures of guns on his cellphone. "I stayed clear of him" in the alternative school because "I didn't want to be with him at all … because of the impression he gave off."
The student added another concern: The suspected gunman had probably participated in the school's active-shooter drills. "He's been in the drills multiple times, so he knows where to go."
Cruz was one of Gard's students for a semester last year, but there was nothing strange about him, the teacher said. "He was quiet in class. I never had any problems."
Investigators are now likely to examine how long the gunman was planning the shooting.
"It is clear [the] attack was designed & executed to maximize loss of life," Sen. Marco Rubio (R-Fla.) tweeted after receiving a briefing from federal investigators. "In days ahead will become increasingly evident that [the] killer in today's #FloridaSchoolShooting gave plenty of indications of what was to come."
An Instagram account belonging to "cruz_nikolas" was taken down shortly after the shooting. The account included photos of a young man wearing U.S. Army hats posing with guns and knives, his face mostly concealed.
In posts, he appeared to be feuding with others, talked about background checks and plans to purchase a rifle he would outfit with a scope "for hunting." Posts included a photo of the definition of the Arabic phrase Allahu Akbar, "God is Great" — with the poster's own mocking caption, including an anti-Muslim slur. Another post included a target riddled with bullet holes labeled "Group Therapy."
The attack was the eighth-deadliest mass shooting in modern U.S. history, with seven of the 10 deadliest happening since 2007.
President Trump tweeted about the shooting and said he had spoken to Gov. Scott.
"My prayers and condolences to the families of the victims of the terrible Florida shooting. No child, teacher or anyone else should ever feel unsafe in an American school," Trump tweeted. "We are working closely with law enforcement on the terrible Florida school shooting."
Times staff writers Pearce, Cosgrove and Finnegan reported from Los Angeles and Hennessy-Fiske from Houston. David Fleshler, Aric Chokey, Lisa J. Huriash and Linda Trischitta contributed from the South Florida Sun-Sentinel.
8:45 p.m.: This article was updated with information about the arrest of the gunman and additional details on fatalities.
8:10 p.m.: This article was updated with an additional witness account.
7:50 p.m.: This article was updated with social media postings on the shooting.
7:20 p.m.: This article was updated with an additional witness account.
6:20 p.m.: This article was updated with additional comments from state officials and law enforcement officers.
4:35 p.m.: This article was updated with information on other mass shootings.
3:35 p.m.: This article was updated with authorities identifying the suspect and saying 17 people were killed.
3:25 p.m.: This article was updated with an additional student account and the latest information from authorities on the suspect and victims.
2:45 p.m.: This article was updated with new information on victims and additional reaction.
1:25 p.m.: This article was updated throughout with Times reporting.
12:20 p.m. This article was updated with details from the scene.