YouTube announced it was banning video tutorials on how to add bump stocks — the device used by Las Vegas killer Stephen Paddock to up his kill count — to guns.

“We have long had a policy against harmful and dangerous content. In the wake of the recent tragedy in Las Vegas, we took a closer look at videos that demonstrate how to convert firearms to make them fire more quickly and we expanded our policy to prohibit these videos,” a spokesperson for YouTube told TechCrunch.

The modification allows semi-automatic weapons to fire like fully automatic weapons, by using the gun’s kickback to activate the trigger more rapidly.

Gunman Stephen Paddock had tricked out at least one of the 23 firearms found in his hotel room with a “bump stock,” which allowed him to fire as many as nine rounds per second.

Google-owned YouTube already has a ban on videos that link to the sale of firearms and bump stocks and is expanding its guidelines to include instructional videos.

As of Wednesday, some videos showing how to convert guns into automatic weapons remained up on the site.

YouTube did not respond to a question asking whether they would remove the existing videos.

Company guidelines prohibit content that could incite violence or dangerous and illegal activities like videos that feature: instructions on bomb-making, choking games, hard drug use and other acts.

“Bump Stocks,” are legal and cost around $100 a pop. Sales for the devices surged after the Las Vegas attack.

Democratic Senator Dianne Feinstein introduced a bill to ban the rifle modifier and though the NRA has called for additional regulations on the device they also said they wouldn’t back her bill.