US President Donald Trump has reiterated his call to arm teachers in the wake of the Florida school shooting, claiming an educator with a weapon would have mowed down the suspected gunman “before he ever knew what happened”.

“Gun-adept” teachers, coaches, and other school workers should be allowed to carry a concealed weapon on campus to deter school shooters, Mr Trump told a cheering crowd at the Conservative Political Action Conference (CPAC).

“This would be a major deterrent because these people are inherently cowards,” he said of shooters. “If [the Florida gunman] thought that other people would be shooting bullets back at him, he wouldn’t have gone there.”

He added: “A teacher would have shot the hell out of him before he ever knew what happened."

The president was referring to suspected gunman Nikolas Cruz, a 19-year-old former student at Marjory Stoneman Douglas High School, where he is alleged to have shot and killed 17 students and staff members last week.

Florida shooting – in pictures Show all 10 1 /10 Florida shooting – in pictures Florida shooting – in pictures Police arrest a suspect in connection with the shooting at the Marjory Stoneman Douglas High School in Parkland, Florida Reuters Florida shooting – in pictures Parents wait for news after reports of a shooting at Marjory Stoneman Douglas High School in Parkland, Florida AP Florida shooting – in pictures Anxious family members wait for news of students AP Photo/Wilfredo Lee Florida shooting – in pictures Students being evacuated from the school AP Florida shooting – in pictures Students being evacuated from the school Getty Florida shooting – in pictures People gather waiting for word from students AP Florida shooting – in pictures Parents waiting for news on their children AP Florida shooting – in pictures People gather at a hotel where students were taken after the shooting Getty Florida shooting – in pictures Florida Governor Rick Scott speaks to the media as he visits Marjory Stoneman Douglas High School following the shooting AFP/Getty Florida shooting – in pictures Dr. Igor Nichiporenko, Medical Director Trauma, left, and Dr. Evan Boyer, Medical Director, Emergency Services, speak about treating victims and the suspect at a press conference outside Broward Health North hospital AP

In the wake of the shooting, many of the student survivors marched and lobbied for stricter gun control laws. Mr Trump responded by proposing expanded background checks for gun purchases, and a ban on automatic rifle sales to anyone under 21. He has also floated – in listening sessions, on Twitter, and most recently at CPAC – giving guns to school workers.

“When we declare our schools to be gun free zones, it just puts our students in far more danger,” he told the major conservative conference on Friday.

The president also claimed his idea had been misrepresented in the media as a call to arm every teacher. Instead, Mr Trump said, he wanted concealed carry permits for the 10 to 20 percent of teachers who are “very gun-adept people”. He did not indicate how he arrived at this number.

“These teachers love their students, and these teachers are talented with weaponry and with guns,” Mr Trump said.

Donald Trump: Florida school deputy 'did a poor job' and lacked 'courage'

Teachers and health policy experts alike have panned the idea since Mr Trump first suggested it, claiming an increase in guns on campus would make schools more dangerous, not less. Some have pointed out that an armed sheriff's deputy was on patrol at Stoneman Douglas the day of the shooting, and failed to confront the gunman.

In his speech on Friday, Mr Trump slammed Deputy Scot Peterson stayed outside the building while the shooting occurred. Broward County Sheriff Scott Israel said on Thursday that Mr Peterson remained outside “for upwards of four minutes.” The shooting, Mr Israel said, lasted six minutes. Mr Peterson had been placed on leave, pending an investigation of his actions - but instead resigned from the sheriff's office.

“He didn’t turn out to be too good, I will tell you that,” Mr Trump said of Mr Peterson. “He was not a credit to law enforcement.” Before heading to CPAC, Mr Trump had suggested to reporters outside the White House that Mr Peterson was either a “coward” or a man who had not fared well under extreme pressure

But Mr Trump also turned the argument back around, claiming that the real issue was with arming outside security officers, rather than teachers inside the classroom.

"I'd rather have somebody who loves their students and wants to protect their students than someone standing outside who doesn’t know anybody," he said.

The proposal puts Mr Trump slightly at odds with the National Rifle Association (NRA) – the largest and most powerful guns-rights lobbying group in America. The association was one of the first to suggests providing armed guards in every school after the Sandy Hook school shooting in 2012.

In his own speech at CPAC on Thursday, NRA CEO Wayne LaPierre reiterated the call for armed security in schools, using the association's pet phrase: "To stop a bad guy with a gun, it takes a good guy with a gun."

Teachers across the country have responded to Mr Trump's proposal with the "Arm Me With" campaign, which lobbies for things like better school supplies and increased pay, instead of more guns. Dozens of teachers have posted their wish lists to Twitter and Instagram using the #ArmMeWith hashtag.