President Donald Trump on Friday slammed the deputy sheriff who failed to confront the shooter at a Florida high school last week, saying that he was either “a coward” or froze under pressure.

Florida authorities said Thursday that school resource officer Scot Peterson, an armed officer responsible for the school’s protection, took a position outside the building for the four-minute duration of the shooting, which left 17 people dead.

Trump, who has been advocating arming teachers with concealed weapons to prevent school shootings and is pushing for several limited gun control measures, said that Peterson “didn’t act properly under pressure” or was “a coward.”

The controversial concealed-carry proposal Trump has been advocating for the past two days has long been promoted by the powerful National Rifle Association (NRA), which endorsed Trump during the 2016 presidential campaign.

“The NRA is composed of people that I know very well,” said Trump. “These are good people. In many cases patriots, they love our country. The NRA wants to do the right thing.”

Speaking shortly afterwards at a conservatives’ conference on the outskirts of Washington, Trump reiterated his support for arming teachers with concealed weapons, saying it would be more efficient than “having 150 guards.”

“Why do we protect our banks, our airports and our government buildings but not our schools?” he asked delegates. “It’s time to make our schools much harder targets for attackers.”

Trump said that concealed-carry gun licences for teachers would mean that “this crazy man wouldn’t even have known who has it [and] a teacher would have shot the hell out of him before he knew what happened.”

Later on Friday at a news conference alongside Australian premier Malcolm Turnbull, the leaders were quizzed on whether the US could learn from Australia’s experience with gun control.

In the wake of a mass shooting in 1996, the Australian government enacted sweeping gun control measures including a massive buyback of semi-automatic shotguns and rifles. There has been no mass shooting since.

“We are very satisfied with our laws,” Turnbull responded. “We certainly don’t presume to provide political advice on that matter here … I wish you wise deliberation in your own country.”

Trump said the US and Australia had “very different sets of problems and we are well on the way to solving that horrible problem,” and promptly ended the press conference.

Confessed 19-year-old shooter Nikolas Cruz killed 17 people and injured more than a dozen others at Marjory Stoneman Douglas High School in Parkland, Florida, last week, prompting a student-led movement for more rigorous gun control.