During a press conference, Broward County Sheriff Scott Israel said at least 17 people died in the shooting at Marjory Stoneman Douglas High School in Florida on Wednesday.
At least 12 of those deaths occurred in the school itself. Two people died in the hospital, and three others died outside the school building.
“There are people that are still undergoing surgery and just pray for this city, pray for this school, the parents, the folks that lost their lives,” Israel said. “It's a horrific, horrific day.”
Both students and adults were among the victims, he said.
Israel confirmed the suspect's identity as 19-year-old Nikolas Cruz, a former student who was expelled for disciplinary reasons.
Cruz, who authorities apprehended shortly after the shooting, was hospitalized and, Israel thought, didn't have significant injuries.
Israel said Cruz used at least one firearm — an AR-15 rifle — and had “multiple magazines” with him. He did not know if Cruz had a second firearm.
Investigators, Israel said, started looking into Cruz's social media presence.
“Some of the things that have come to mind are very, very disturbing,” he said.
One student, who claimed to be Cruz's former classmate, said he was “troubled.”
“He’s always had a certain amount of issues going on. He shot guns because he felt it gave him, I guess, an exhilarating feeling,” the unidentified student said.
Jim Gard, a math teacher who said the shooter was in his class last year, said “there were problems with him last year threatening students.”
Cruz, Gard recalled hearing, wasn't allowed to go on campus with a backpack.
During his press conference, Israel asked the public to report seeing behavioral changes or disturbing social media content.
“If anybody has any indicator that someone's going through a behavioral change, or on their social media that there are disturbing photos — perhaps bombs or firearms — or just videos or pictures that are just not right, please make sure law enforcement knows about it.”
Watch the press conference above, via CNN.