The initial confusion and panic among police responding to the Las Vegas massacre has been revealed in body-worn camera footage that shows officers crouching behind walls and yelling at screaming bystanders to get down as bullets rained around them.
The Las Vegas Metropolitan Police Department released snippets of footage on Wednesday taken from police officers who had responded to the shooting but couldn't determine where the gunfire was coming from.
Investigators are looking through footage from 67 body-worn cameras and Fairfax Media understands that footage from one camera has captured up to 15 separate rounds of fire.
Retired accountant and high-stakes gambler Stephen Paddock, 64, opened fire on the Route 91 Harvest country music festival just after 10pm on Sunday from his room in the Mandalay Bay Resort and Casino, about 450 metres away.
The gunfire lasted for between nine and 11 minutes, police said.
In the body-worn footage, officers take shelter behind police cars and brick walls while volleys of fire continue to ring out.
Paddock had brought 23 guns into his hotel room concealed in at least 10 suitcases. A spokeswoman for the Federal Bureau of Alcohol, Tobacco and Firearms (ATF) said on Wednesday that Paddock had 12 "bump stock" devices to modify rifles to make them discharge ammunition more quickly.
He had a total of 47 firearms across the hotel room and his two homes in Nevada.
All were purchased legally at gun stories in Nevada, California, Utah and Texas, the ATF spokeswoman said. The bump stocks were also legal, she said.
Earlier on Wednesday, photos emerged showing the inside of the hotel room strewn with guns, bullets, magazines and Paddock's body . Police confirmed the images were legitimate.
It was also revealed that Paddock set up a network of cameras to be able to see when law enforcement officers were approaching. Two were set up in the hallway and one was placed in the hotel room door peephole.
Undersheriff Kevin McMahill said a hotel security guard, who became separated from a group of officers searching the floors, was shot through the door by Paddock and hit in the leg.
He believed that the guard's approach made Paddock turn his attention away from shooting the crowd and allowed officers to narrow in on his hotel room.
A motive for the shooting is still unknown. Paddock's Australian-Filipino girlfriend Marilou Danley, 62, is expected to arrive from the Philippines this week and will face questioning.
Paddock has emerged as a multimillionaire gambler and a loner who, in the days leading up to the shooting, had made several casino wins of more than $US10,000 a day and had wired $US100,000 to the Philippines.