So far, the ISIS claim has not held up to scrutiny, raising the question of why the terrorist group would claim responsibility for an attack it didn't commit.
A second post, which experts say is a rare occurrence for an ISIS claim, said that the "attacker of Las Vegas converted several months ago". "The idea that the Islamic State simply scans the news in search of mass killings, then sends out press releases in hope of stealing glory, is false", Atlantic National Correspondent and author Graeme Wood noted Monday on why the claim should be taken seriously. Moreover, the report says that in a statement ISIS referred to Paddock by the nom de guerre Abu Abd al-Barr al-Amriki.
More than 50 people have been confirmed dead and 200 injured in the shooting, making it the deadliest in United States history.
Unlike previous attacks claimed by ISIS, there is no indication Paddock had religious or political inclinations, nor did he leave a video message of himself pledging allegiance as some attackers have.
The terrorist group published at least one English video on October 3 about the Las Vegas attack. Paddock killed himself as police closed in, making it easier for ISIS to make the claim. It turned out to be a botched robbery by a heavily indebted Filipino gambling addict.
A 46-minute audio recording appeared to show Abu Bakr al-Baghdadi praise the jihadis killed in the battle to retake Mosul and other former Isis territories.
Before Sunday, the deadliest mass shooting in modern USA history took place in June 2016, when a gunman who professed support for Muslim extremist groups opened fire at a gay nightclub in Orlando, Florida, killing 49 people.
He urged followers to "intensify one attack after another against the infidels", following a spike in global terror attacks.
An intercepted ISIS communication from October 2 claims credit for the shooting in Las Vegas on October 1.
Rouse was reacting to a statement ISIS released earlier, which read: "The Las Vegas attack was carried out by a soldier of the Islamic State and he carried it out in response to calls to target states of the coalition". He said of renewed calls for greater gun control that "we'll be talking about gun laws as time goes by". "This is merely a way to garner more attention. even though the claim is patently. false".