President Donald Trump said Tuesday he is moving to impose new regulations that would ban devices that allow certain firearms to function as rapid fire “machine guns,” in the wake of the mass shooting at a Florida high school that left 17 people dead.

Mr. Trump, speaking at an event in the White House, said he had signed a memorandum directing Attorney General Jeff Sessions to develop regulations that would ban the sale and use of “bump stocks.” While that accessory wasn’t used in last week’s Florida shooting, it was used in the Las Vegas gun massacre in October that stands as the deadliest in U.S. history.

In a statement, the Justice Department said it grasps that “this is a priority for the president and [it] has acted quickly to move through the rule-making process. We look forward to the results of that process as soon as it is duly completed.”

The deadly shooting last Wednesday at Marjory Stoneman Douglas High School in Parkland, Fla., thrust gun laws back into the spotlight. A 19-year-old former student there admitted to killing 17 students and school employees. He was armed with an AR-15 style rifle, according to a complaint affidavit released Thursday.

Following the shooting, Mr. Trump is facing renewed pressure to take action that would safeguard the nation’s schools, with students around the country staging demonstrations and urging stricter gun-control measures. Although he was a staunch supporter of gun rights during the 2016 campaign, Mr. Trump is signaling a new openness toward gun restrictions amid a string of mass shootings.