The Justice Department on Tuesday issued its final rule banning bump-fire stocks. The firearms accessory came to national attention last October after a gunman in Las Vegas unleashed murderous gunfire on concertgoers, killing 58 people.

The device makes it easier to fire rounds from a semi-automatic weapon by harnessing the gun’s recoil to “bump” the trigger faster.  Pro-gun advocates have said they are prepared to fight the rule in court.

“We are faithfully following President Trump’s leadership by making clear that bump stocks, which turn semiautomatics into machine guns, are illegal, and we will continue to take illegal guns off of our streets,” acting attorney general Matt Whitaker said in a statement Tuesday.

Bump stock owners will have 90 days to destroy their devices or to turn them in by March 21.

President Donald Trump directed the Department of Justice to look into changing regulations so that bump stocks would be classified as machine guns this past spring following a deadly Valentine’s Day shooting at a high school in Parkland, Florida, that left 17 dead. Machine guns are illegal to possess in most cases.

The rule amends the regulations of the Bureau of Alcohol, Tobacco, Firearms, and Explosives to include all bump-stock-type devices and re-classify them as machine guns. Officials at the Bureau of Alcohol, Tobacco, Firearms and Explosives had previously concluded bump stocks were merely a gun accessory or firearm part, not subject to federal regulation.