According to a report from News Week, the police were already on high alert:
Las Vegas authorities were already on high alert before the shooting attack on the city’s famous strip on Sunday night that left at least 20 people dead at the Route 91 Festival, after the Islamic State militant group (ISIS) released a propaganda video earlier this year showing footage of the site.
The 44-minute-long video released in May showed footage of the Las Vegas strip from 2015, calling on its supporters to conduct attacks with knives and vehicles, everyday weapons that its supporters have already used many times in the West over the past several years. The footage also showed New York City and Washington, D.C.
No group has yet claimed responsibility for the attack on Sunday, but the footage prompted authorities to consider that there was a credible threat to the city popular with tourists and gamblers.
The FBI also commented:
The FBI’s Las Vegas field office told Fox News in a statement following the video’s publication that it was working with “international law enforcement, intelligence, and security services agecies to share information and intelligence.”
A spokesperson for the Las Vegas Metropolitan Police Department said: “We are always concerned when Las Vegas is mentioned by groups or individuals who subscribe to the idea of committing violence to further their cause.
“Our city has been mentioned in similar videos and publications but this most recent video should serve as a reminder to remain vigilant and to report any suspicious activity.”
Now, this comes after AP broke the news that ISIS claimed responsibility for the attack although they did mention that ISIS has no evidence to back up that claim.