WASHINGTON (Reuters) - The Justice Department is proposing rule changes that will effectively ban bump stocks, devices that allow semi-automatic weapons to fire like a machine gun, U.S. Attorney General Jeff Sessions said on Friday.

FILE PHOTO: Attorney General Jeff Sessions speaks to the National Association of Attorneys General 2018 Winter Meeting in Washington, U.S., February 27, 2018. REUTERS/Joshua Roberts/File Photo

“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,” Sessions said in a statement.

Sessions has been a defender of the U.S. Constitution’s Second Amendment, which protects the right to bear arms.

Gunman Stephen Paddock used a bump stock in a massacre last October that killed 58 people and wounded hundreds of others at a music festival in Las Vegas.

Authorities said Paddock’s ability to fire hundreds of rounds per minute over a 10-minute period from his 32nd-floor hotel suite was a major factor in the high casualty count.

In February, President Donald Trump signed a memorandum directing the Justice Department to make the regulatory change.

“As I promised, today the Department of Justice will issue the rule banning BUMP STOCKS with a mandated comment period,” Trump said on Twitter as the announcement was made. “We will BAN all devices that turn legal weapons into illegal machine guns.”

The National Rifle Association, the most powerful U.S. gun lobby, supported more regulation of bump stocks but has not endorsed Trump’s ban and said previously it was awaiting the publication of the regulation before rendering judgment.

The Justice Department announcement comes as hundreds of thousands of Americans are expected to rally nationwide on Saturday for tighter gun laws in “March For Our Lives” protests led by survivors of the Florida school massacre, which reiginited the debate over Americans’ access to guns.

Students from the Parkland, Florida, high school where 17 students and staff were killed on Feb. 14 will be among the 500,000 people who organizers say could rally on Pennsylvania Avenue near the Capitol in Washington.