Police also told a news conference today that 317 of the 489 people injured in the Las Vegas shooting had been discharged from hospitals and the death toll of 59, including gunman Stephen Paddock, remained the same.
Sheriff Joseph Lombardo said Paddock, 64, had 1600 rounds of ammunition and several containers of an explosive commonly used in target shooting that totalled about 22kg in his car.
He said none of the cameras he put up in the hotel room where he unleashed gunfire on to a concert crowd across the Las Vegas Strip on Sunday night were recording.
Police admit they are still trying to find any reasons why Paddock committed the atrocity.
They say Paddock lived a mysterious last 10 years and did not have a lot of personal relationships, the Las Vegas Review Journal's Rachel Crosby reports.
Las Vegas Metropolitan Police Sheriff Joseph Lombardo confirmed Paddock rented a room at The Ogden through AirBnB during Life is Beautiful, headlined by Kiwi songstress Lorde. It's still unclear why, he said.
Lombardo told a press conference "anything that would indicate this individual's trigger point and that would cause him to do such harm, we haven't understood it yet".
"Usually there is a telltale sign associated with these type of actions ... We have not found that yet."
He confirmed it was a well-planned attack.
"This is well thought out. Don't you think the concealment of his history or his life was well thought out?"
He said it was "troublesome that this individual was able to move this amount of gear into a hotel room unassisted.
"Relationship-wise, it is very hard to determine what has occurred in his life in the last decade or so," he added.
The FBI's Aaron Rouse said they were aware Paddock was gambling before the shooting.
"When we did see he was gambling, we did not see another individual appearing there."
They added, "You've got to make the assumption that he had to have some help at some point."
They said, "We haven't been able to determine if there has been anybody else in the room besides him."
They were investigating multiple leads across the United States and the world but said: "We cannot give in to conjecture and we cannot respond to every little Twitter feed that may indicate a theory."
