"Every detail of this indiscriminate mass murder seemed meticulously planned," the local media reported.
However, the Clark County sheriff told reporters he thinks the shooter might have used them to watch for people approaching his room.
Investigators probing the Las Vegas massacre have searched gunman Stephen Paddock 's home and recovered 42 firearms, an assortment of explosives and several thousand rounds of ammunition from his Las Vegas hotel room and his Mesquite home.
The Las Vegas mass shooting is the deadliest mass shooting in modern American history, claiming the lives of 59 people and injuring 527 others.
Investigators believe Paddock, who fired into a crowd of thousands during a country music festival from a Las Vegas hotel suite, used bump-stock for the attack as it modifies a semi-automatic weapon to fire at an automatic rate, the Guardian reports.
There is still no known motive behind the attack or any known links between Paddock and other terror organisations.
Authorities said he acted alone, but the attacker's girlfriend Marilou Danley will be interviewed after she returns from Tokyo.
Describing the shooting as "an act of pure evil", United States President Donald Trump said he would visit Las Vegas on Wednesday and will meet with the first responders to the attack. President Trump has ordered for American flags at the White House and at public buildings nationwide to be flown at half mast.
Sheriff Joe Lombardo said investigators are focused on four main crime scenes right now: The room at Mandalay Bay hotel from where the gunman shot, the concert event location, the shooter's house in Mesquite, Nevada, and a home in northern Nevada, the CNN reported.
Some electronic devices have also been retrieved and are being evaluated, he added.
A North Las Vegas gun store sold a shotgun and a rifle to Paddock in spring. All state and federal requirements, including a FBI background check, were met,CNN quoted David Famiglietti, president of New Frontier Armory, as saying. He said that neither of the weapons "leaving our store are capable of what we've seen and heard in the video without modification."(ANI)