Seventeen people were killed when a former student went on a shooting rampage at a high school Wednesday in Florida, authorities said.
The first shots were fired around 2:40 p.m. at Marjory Stoneman Douglas High School in Parkland, an affluent community in northwest Broward County, the Sun Sentinel newspaper reported.
In a grainy Snapchat video from the school, someone yells, "Oh, my God," as gunfire erupts and students scream.
The shooter, identified as 19-year-old Nikolaus Cruz, was armed with an AR-15 rifle and multiple ammunition magazines, said Broward County Sheriff Scott Israel.
The victims included students and adults. Twelve of the dead were found inside the school. Two were killed outside the school. Two others died at the hopsital. One more person was killed off the school's campus.
At least 16 people were being treated at local hospitals. Five were in critical condition.
Cruz, dressed in a red shirt, black pants, and black boots, was arrested several miles from the school and was first taken to an area hospital and then transferred to the Broward Sheriff's Office headquarters in Fort Lauderdale.
Israel said at a briefing to news media that Cruz had been expelled from this high school for disciplinary reasons.
Math teacher Jim Gard told the Miami Herald that he taught Cruz last year and said he was a troubled student.
"We were told last year that he wasn't allowed on campus with a backpack on him," Gard said.
"There were problems with him last year threatening students, and I guess he was asked to leave campus," Gard said.
Investigators were scouring Cruz's social media accounts for clues connected to the shooting, Israel said.
The material they had found so far was "very, very distubring," Israel said.
Helicopter news videos showed students rushing out of the school in single-file lines with their hands placed on the shoulders of the person in front of them. They threw backpacks into piles and huddled under trees across the street.
Parents described the frightening situation as they rushed to find their children.
Caesar Figueroa told the Associated Press that he was one of the first parents to arrive at the school. He saw police officers bringing out big weapons as they approached the school.
"My wife called me that there was an active shooter and the school was on lockdown. I got on the road and saw helicopters, police with machine guns. It was crazy and my daughter wasn't answering her phone."
Figueroa said his daughter texted him that she was hidden inside a closet at school with friends.
"She was in a classroom and she heard gunshots by the window. She and her friends ran into the closet," Figueroa said.
President Trump tweeted: "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."