PARKLAND, Fla. — President Trump said on Thursday that he would make school safety the top priority when he meets with the nation’s governors later this month, following one of the deadliest school shootings in modern American history.
In the address to the nation, he also said he planned to visit the grieving South Florida community where a gunman killed 17 students and adults at a local high school. But he pointedly avoided any mention of gun control.
“We are here for you — whatever you need, whatever we can do, to ease your pain,” Mr. Trump said, calling the deaths at Marjory Stoneman Douglas High School in Parkland a “scene of terrible violence, hatred and evil.”
• Nikolas Cruz, who barged into his former high school with a semiautomatic AR-15 rifle on Wednesday afternoon, was charged on Thursday with 17 counts of premeditated murder, one for each of the students and adults he killed.
• Mr. Cruz, 19, was booked into jail in Broward County and the authorities released a mug shot of him staring wide-eyed into the camera.
• The F.B.I. on Thursday said it received information about a comment made on a YouTube channel which has been attributed to the gunman, but were unable to identify the person.
• Gov. Rick Scott of Florida said he would meet with state lawmakers to secure more funding for school safety and the treatment of mental illness.“If we have somebody that’s mentally ill, they can’t have access to a gun,” Mr. Scott said.
• The authorities said the AR-15 rifle that Mr. Cruz used in the attack was purchased legally. “No laws were violated in the procurement of this weapon,” said Peter J. Forcelli, the special agent in charge for the Bureau of Alcohol, Tobacco, Firearms and Explosives in Miami.
• With the Parkland shooting, three of the 10 deadliest mass shootings in modern United States history have come in the last five months. Here is a graphic that records the grim toll of school shootings across the nation.
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The F.B.I. had information about a suspicious comment on YouTube.
Ben Bennight, a bail bondsman in Mississippi, said in a video posted Wednesday that he reported a suspicious comment left on his YouTube channel last fall by a user named “nikolas cruz.”
“I’m going to be a professional school shooter,” the Sept. 24 comment said.
Mr. Bennight took a screenshot of the comment and flagged it to YouTube, which removed the post. Then, Mr. Bennight said he left a voice mail message at his local F.B.I. field office alerting them about the comment.
Mr. Bennight, 36, spoke briefly with The New York Times on Thursday. He said when he originally reported the comments to the F.B.I., a pair of agents interviewed him the next morning. Mr. Bennight said two F.B.I. agents visited him a few hours after the shooting on Wednesday, spending about 15 to 20 minutes with him. The agents told him they thought the person who posted on his channel might be connected to the Florida shooting because they had the same name.
The F.B.I. on Thursday released a statement that said it received information about a comment made on a YouTube channel in September 2017. “No other information was included in the comment which would indicate a particular time, location, or the true identity of the person who posted the comment,” the statement said. The F.B.I. said it conducted database reviews and other checks, but were unable to further identify the person who posted the comment.
Mr. Bennight did not fault the F.B.I., he said.
“We live in a country where you can’t just lock people away for saying something,” he said. “You can’t just stuff somebody in a black hole because they said something that makes you uncomfortable. I believe the F.B.I. took it seriously. I hope that they followed up.”
He added the number of school shootings is a frightening prospect for any parent. “It scares me for my children,” he said.
The president calls the gunman ‘mentally disturbed.’
Mr. Trump, in a Twitter post early Thursday, said that people should report anyone behaving like Mr. Cruz to the authorities.
“So many signs that the Florida shooter was mentally disturbed, even expelled from school for bad and erratic behavior,” Mr. Trump said. “Neighbors and classmates knew he was a big problem. Must always report such instances to authorities, again and again!”
In a statement on Thursday, Mr. Trump called for the American flag to fly at half-staff at the White House and other public buildings and grounds as a sign of respect for the shooting victims. “Our nation grieves with those who have lost loved ones” in the Florida shooting, he said.
Without offering any specific proposals, the attorney general, Jeff Sessions, said on Thursday,“We’ve got to reverse these trends we’re seeing in these shootings.”
He added that the Justice Department was prepared to enforce existing gun laws and that he met with officials from the Health and Human Services and Education Departments on Thursday to study “the intersection of mental health and criminality and violence.”
The gunman said ‘I don’t go to school on Valentine’s Day,’ according to a lawyer.
On weekday mornings, Mr. Cruz usually got up to catch a ride to the adult education courses that the family he had stayed with after his mother’s death last year had encouraged him to attend, the family’s lawyer, Jim Lewis, told CNN. But on Wednesday, he refused to get up, Mr. Lewis said.
Mr. Lewis said that Mr. Cruz explained his reluctance by saying something to the effect of “It’s Valentine’s Day. I don’t go to school on Valentine’s Day.”
He had been staying with the family since November, the month his mother, Lynda Cruz, died. Mr. Lewis said that the family had seen signs of depression in Mr. Cruz, but nothing indicated that he was capable of this kind of violence. The family had allowed Mr. Cruz to bring his gun with him to their house, insisting that he keep it in a lockbox.
“This family did what they thought was right which was take in a troubled kid and try to help him,” he said.
That included Mr. Lewis encouraging Mr. Cruz to attend adult education courses and work toward his G.E.D. As the months wore on, the family thought his mood seemed to be improving. Though they were aware that he had disciplinary problems at his former school and there were some indications that he had been bullied, he had never shared contempt for the school or anyone there with them.
In the hours after the shooting, people who knew Mr. Cruz described him as a “troubled kid” who enjoyed showing off his firearms, bragging about killing animals and whose mother would resort to calling the police to have them come to their home to try to talk some sense into him.
Democrats are repeating their calls for tougher gun legislation.
Senator Richard Blumenthal, Democrat of Connecticut, disputed Mr. Trump’s gesture toward mental health, pointing out the high rates of gun violence in the United States compared with other countries.
In an appearance on CNN, Mr. Blumenthal said that after the Sandy Hook school shooting in 2012, Connecticut worked to cut down on gun violence by passing measures to ban assault weapons and increase background checks.
But he said that even states that had worked to improve gun safety were vulnerable. “We are at the mercy of the weakest states, even when we have the strongest gun laws,” he said.
Senator Bill Nelson of Florida, in an appearance on CNN, railed against the inability of his state to pass effective legislation to help prevent attacks like the one on Wednesday. He pointed out that, with the Pulse shooting in Orlando that killed 49 and a shooting at the Fort Lauderdale airport that killed five, it was the third mass shooting attack in the last couple of years in Florida alone.
“We’ve been through this a lot and each time we say enough is enough and then of course it isn’t enough,” he said.
‘If I don’t make it, I love you,’ a student tells her mother.
Many students used their phones to keep their parents informed about what was happening, and to document some of the violence that was unfolding around them.
Sarah Crescitelli, a freshman, was in drama class rehearsing for a musical when gunshots rang out.
Hiding in a sweltering storage room with about 40 other students, she typed out a text message to her mother, Stacy, for what she thought might be the last time.
“If I don’t make it,” she wrote, “I love you and I appreciate everything you did for me.”