President Donald Trump on Friday said his administration will ban bump stock devices that "turn legal weapons into illegal machines."
The Justice Department announced that it has started the process to amend federal firearms regulations to clarify that federal law defines bump stocks as machine guns.
Trump had ordered Justice to work toward a ban after the Florida high school shooting. Bump stocks enable guns to fire like automatic weapons, and were used in last year's Las Vegas massacre.
Trump tweeted Friday: "Obama Administration legalized bump stocks. BAD IDEA. As I promised, today the Department of Justice will issue the rule banning BUMP STOCKS with a mandated comment period."
The government determined in 2010 that bump stocks couldn't be regulated unless Congress changed the law.
"After the senseless attack in Las Vegas, this proposed rule is a critical step in our effort to reduce the threat of gun violence that is in keeping with the Constitution and the laws passed by Congress," said Attorney General Jeff Sessions.