Some 1,200 pages of reports were made public by Las Vegas police following a US court order.
They described the experiences of witnesses and victims on 1 October last year, when Stephen Paddock opened fire from the 32nd floor of a hotel, killing 58 people and injuring more than 800.
Paddock later killed himself before he could be arrested.
About 22,000 people were attending the Route 91 Harvest Festival concert that night, and many told police that they initially thought the gunshots were firecrackers.
One woman (names are blacked out in the police documents) told police: "There was a noise to our right.
"And everybody just kept yelling, like: 'Oh, it's fireworks'.
"A couple of seconds later, um, I fell to the ground and I couldn't feel my arm."
In her statement, reported in US media, she added: "Within seconds of that, like, the second round of bullets came through and everybody just hit the ground."
Another woman said: "I was laying next to my mom and she said: 'I got hit, I got hit'.
"I then saw blood come out of her mouth."
According to the Los Angeles Times, one statement was from a man who described being at the concert with his wife and daughter. His wife was shot in the back.