"We heard the bullets hitting the ground next to us and we could see the spark and the smoke, you could hear that thump of a bullet hitting somebody," McInerney told reporter Tim Rosaforte on Golf Channel program Golf Central.
The 23-year-old was with a large group of friends including his girlfriend at the open-air concert in Las Vegas when the shooting began.
"Everybody kind of turned around their shoulder and looked to the right and kind of wondering who's bringing fireworks into a country concert.
"And next thing you knew, a guy that was standing about 20 feet away from us, yelled at the top of his lungs and said, 'those aren't fireworks, everybody get down,' and we just hit the ground.
"The shooting went on for about close to a minute and he had a full automatic weapon.
"He was just blowing the place up.
"When it let up for just a second, so assuming he was reloading, we got up and we just ran for our lives.
"We ran to my car which was parked at the MGM and we were hopping walls, people were throwing rocks through buildings just trying to get inside and get shelter."
McInerney says he encouraged several strangers into his car before driving away to safety.
"We saw pick-up trucks driving up and down Las Vegas Boulevard just picking up people that were literally running for their lives down the middle of one of the busiest streets in Las Vegas."
"Once I knew I was kind of in my car and kind of away, that's when I knew I'd be alright."
Saw a few people down and bullets hitting the ground everywhere. I'm lucky to be alive. Praying for everyone. #VegasStrong— AJ McInerney (@AJ_McInerney) October 2, 2017
McInerney says it wasn't until as late as 8am the following morning that he was able to account for some of his friends.
"I'm so lucky that me and the people I love most weren't physically harmed, we're just pretty emotionally shaken. But there's so many people out there that weren't as lucky and this needs to be about them."
"There's so many families and so many people that need our help and that's how my outlook on this has been.
"We're going to have scars for the rest of our lives, so I don't think it's quite hit us how much or how far it's going to affect us.
McInerney - who turned pro in 2016 - finished 97th on this year's Web.com Tour money list.
He said he plans to tee it up at the second stage of Web.com Tour Q-School later this year in an effort to regain full playing rights on the secondary US tour for next season.
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