He said that the U.S. must “tackle the difficult issue of mental health,” but offered no specifics.

“It is not enough to simply take actions that make us feel like we are making a difference. We must actually make that difference,” he said.

The 19-year-old gunman, Nikolas Cruz, attacked Marjory Stoneman Douglas High School in Parkland, Florida on Wednesday. It was the deadliest school shooting since 20 children and six adults were killed in the December 2012 rampage at Sandy Hook Elementary School in Newtown, Connecticut.

Authorities said the Florida shooter used a semiautomatic AR-15-style rifle that he bought legally. Similar guns have been used in many mass shootings, including in Las Vegas last year and Orlando in 2016.

Trump didn’t immediately appear on television after the shooting, instead tweeting a series of reactions. Earlier on Thursday he appeared to blame people around Cruz for not doing more to prevent the incident.

“So many signs that the Florida shooter was mentally disturbed, even expelled from school for bad and erratic behavior,” he wrote on Twitter. “Neighbors and classmates knew he was a big problem. Must always report such instances to authorities, again and again!”

News reports suggest that school officials, classmates and even strangers were concerned that Cruz could pose a threat. A teacher told the Miami Herald on Wednesday that administrators sent an email last year saying that Cruz was not allowed to carry a backpack on campus. BuzzFeed News reported Thursday that a YouTube user was interviewed by the FBI after alerting the bureau to a comment from a user named Nikolas Cruz that read “I’m going to be a professional school shooter.”

Addressing children who may be frightened by the shooting, Trump said that “if you need help, turn to a teacher, a family member, a local police officer or a faith leader. Answer hate with love, answer cruelty with kindness.”

As president, Trump has opposed any new restrictions on gun rights. Last year he signed a bill revoking Obama-era regulations banning gun purchases by people who receive Social Security disability checks for mental illness or who have been determined unfit to handle their own finances. President Barack Obama proposed the rule after the Sandy Hook shooting and his administration anticipated that it would have added 75,000 names to the national background check database.

In an interview last month with Piers Morgan, Trump defended permissive U.S. gun laws.

“If he didn’t have a gun, he would have a bomb, or would have something else,” Trump said of Stephen Paddock, who killed 58 and wounded hundreds by firing on a concert from a Las Vegas hotel room in October, where he had stockpiled an arsenal of 55 guns.

“The point is, he would have had 55 bombs. He would have had 55 of something else,” Trump said.

After the Las Vegas shooting, in October, White House press secretary Sarah Huckabee Sanders said the immediate aftermath of a tragedy wasn’t the time to talk about gun policy, the same stance Republicans including Florida Governor Rick Scott adopted after Wednesday’s shooting.

“There’s a time to continue to have these conversations about how through law enforcement, how through mental illness funding, that we make sure that people are safe,” Scott said at a news conference Wednesday in Parkland, Florida, according to The Hill. He declined to address questions about gun control, The Hill said.

Republicans and Democrats alike in Washington discussed banning a piece of equipment Paddock used to fire more rapidly, called a bump stock, after the Las Vegas shooting. But the issue soon receded as Congress instead focused on a tax overhaul and funding the government, and no new gun laws have been passed.

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