Sorry, I have to interject on this one. My nephew and his friends - all in their 20s, so grown men size-wise - were on the opposite side of where everything was happening and didn't see a thing. The concert ended about the time that it was scheduled to end - it wasn't going to be an "until midnight or so concert". They walked out calmly, even having a casual conversation with other attendees, and got in their car and left. They never saw the ambulances on the streets. When they got to their hotel room and checked their phones, they found out what had happened. Now, yes, there was a lot of pushing and shoving, as what usually happens at these types of concerts, but they didn't experience anything out of the ordinary.
I questioned him at length because I wanted to make sure that none of them felt any strange effects, since there was talk at first of people being revived with Narcan and there was speculation that someone was going through the crowd injecting people. He said they all felt fine, with only some bumps and bruises from the crowd. I also wanted to make sure that none of them had witnessed people seizing or dying that could have caused them psychological trauma. I can't imagine what some of those kids witnessed.
Oh, and I believe the "ambulances" that were actually in the crowd were more of a golf cart type of vehicle, not your standard ambulance. Those were probably stationed outside the fenced-in area.
Just my observations - no flaming necessary.