President Donald Trump on Friday doubled down on remarks that some teachers should be trained to carry firearms in schools.

In a speech at the annual Conservative Political Action Conference, Trump described the proposal as a "common-sense" measure.

"It's time to make our schools a much harder target for attackers," Trump said. "When we declare our schools to be gun-free zones it just puts our students in far more danger. Well-trained, gun-adept teachers and coaches" should be the ones carrying guns.

"I mean, I don't want to have 100 guards with rifles standing all over the school. You do a concealed carry permit," he added. "This would be a major deterrent, because these people are inherently cowards."

A teacher with a concealed weapon "would have shot the hell out of" the Marjory Stoneman Douglas High School shooter last week in South Florida, Trump said during the speech.

After the 2012 Sandy Hook elementary school massacre in which 20 young children and six adults was gunned down in Connecticut, the National Rifle Association called for putting police officers and armed guards in schools.

During last week's massacre, the armed Broward County officer on duty at the school "never went in" to confront the shooter, Sheriff Scott Israel told reporters Thursday. The officer, Scot Peterson, has resigned, Israel said.

But even as Trump advocated arming teachers with concealed weapons, he criticized the media for wrongly characterizing his proposals.

"I'm not talking about teachers," he said, describing media reports about his position on giving teachers guns as "fake news." He then talked about what kinds of teachers should be armed.

"I don't want a person that's never handled a gun, that doesn't know what a gun looks like, to be armed," he said. Only those who are "gun-adept" — which Trump says could be 10 or 20 percent of teachers — should have guns, he said.

The nation is gripped in a debate over gun control and school security after a gunman wielding an AR-15 semi-automatic last week killed 17 students and adults at a southeast Florida high school.

On Wednesday, Trump hosted a listening session at the White House with the families and survivors of school shootings.

At that event, Trump said teachers with firearms could end an attack "very quickly."

The next day, in seven tweets on the issue of gun policy, Trump strongly advocated arming "only the best" trained teachers with guns in schools.

"20% of teachers, a lot, would now be able to ... immediately fire back if a savage sicko came to a school with bad intentions," Trump tweeted.

During the CPAC speech, Trump also said if Democrats win majority control of congressional House races in 2018, "they will take away your Second Amendment."

And he called for strengthening background checks and preventing "people who are mentally ill from having any form of weapon."