Faced with an outpouring of grief and anger over a deadly school shooting in Florida, US President Donald Trump has threw his support behind moves to ban "bump stocks" -- an accessory that can turn a semi-automatic weapon into an automatic one.

Trump also said school safety was a "top priority" for his administration and he would be holding meetings on the subject this week and also next week, when he meets with governors from all 50 US states.

Calls to ban bump stocks have been mounting since Stephen Paddock, a retired accountant, used them on several of his weapons to kill 58 concertgoers in Las Vegas in October 2017 in the deadliest mass shooting in recent US history.

Although the former student who shot dead 17 people in Florida last week did not have bump stocks on his gun, there has been a renewed focus on the devices because outlawing them is a rare point of agreement between Democrats, some Republicans and the powerful National Rifle Association (NRA) gun lobby.

Trump -- who received strong backing from the NRA during his White House run -- said he had signed a memorandum "directing the attorney general to propose regulations to ban all devices that turn legal weapons into machine guns."

He said he expected them to be finalized "very soon."

"We cannot merely take actions that make us feel like we are making a difference," Trump said at a White House event to honor 12 Americans for heroism. "We must actually make a difference.

"We must move past cliches and tired debates and focus on evidence-based solutions and security measures that actually work," he said. "We must do more to protect our children."

Trump said he would meet this week with students, local leaders, and members of law enforcement to develop "concrete steps" to "secure our schools, safeguard our students, and protect our communities."

"This includes implementing common sense security measures and addressing mental health issues," he said, "including better coordination between federal and state law enforcement to take swift action when there are warning signs.

AFP