The National Rifle Association has joined a growing chorus of organizations and people calling for a review of "bump stock" devices.

Investigators said gunman Stephen Paddock had several bump stocks when he fired upon a Las Vegas concert crowd Sunday evening, killing 58 people and injuring hundreds of others before taking his own life.

The NRA explained Thursday it believed there should be additional regulations for the devices, which can effectively convert semi-automatic rifles into automatic rifles.

"Despite the fact that the Obama administration approved the sale of bump fire stocks on at least two occasions, the National Rifle Association is calling on the Bureau of Alcohol, Tobacco, Firearms and Explosives (BATFE) to immediately review whether these devices comply with federal law," the statement from the NRA's Wayne LaPierre and Chris Cox read.

House Speaker Paul Ryan said earlier in the day that Congress needed to review the devices as well.

"I didn't even know what they were until this week, and I'm an avid sportsman, so I think we're quickly coming up to speed with what this is," Ryan said in an interview on MSNBC. "Fully automatic weapons have been banned for a long time. Apparently this allows you to take a semi-automatic and turn it into a fully automatic so clearly that's something that we need to look into."

The Associated Press contributed to this report