Islamic State claimed responsibility for the mass shooting at a country music festival in Las Vegas, and said the shooter converted to Islam several months ago, according to a group that monitors online terrorist networks.

SITE Intel Group said the terror organization claimed responsibility through its Amaq news agency, although ISIS has yet to offer proof of its claim.

"#BREAKING: #ISIS claimed #LasVegas attack, reporting through ‘Amaq that executor is one of its "soldiers" & he converted to Islam months ago," SITE Intel Group tweeted Monday morning.

BREAKING: #ISIS claimed #LasVegas attack, reporting through 'Amaq that executor is one of its "soldiers" & he converted to Islam months ago pic.twitter.com/4E85vEIUzH

— SITE Intel Group (@siteintelgroup) October 2, 2017

The shooter, identified as 64-year-old Stephen Paddock, fired down on the crowd of concert-goers at the Route 91 music festival from a room on the 32nd floor of the Mandalay Bay Hotel and Casino.

Police said he committed suicide before law enforcement broke into his hotel room.

At least 50 people were killed and more than 400 injured.

SITE noted earlier on Monday that ISIS featured the Las Vegas Strip in a May video, and that an al Qaeda affiliate in 2014 suggested Las Vegas as a target.