The doors weren't chained--they were inadequate for the number of the people who were crowded into the club which thanks to the owners far exceeded it's approved capacity. There was a rear exit door but it was not obvious to most of the clubgoers because the club owners obscured it so only the band members--who were able to escape--could use it. Some clubgoers knew it was there and got out. Everyone else headed for the door they came in through and as a result the door was so tightly crammed with people it was impossible to get out. Many people was crushed to death in the doorway.
This is why it is good practice when in a public place to always know where your closest alternative exits are. Don't depend on getting out in an emergency the way you came in.
The guitar player died when he went back in to try saving his axe.
I hate tightly packed crowds. I experience claustrophobia, feelings of panic, etc.
Many years ago I had gone on a “girls” weekend trip to OC Maryland and the girls I was with, mostly younger than me, wanted to go to a popular night club. The place was jammed with people, so tightly packed, shoulder to shoulder, that you could barely move. After about 10 minutes, I experienced a panic attack, heart pounding, shortness of breath and told one of my friends I needed to get out.
I told her I’d wait for them in the car or outside or take a walk on the beach instead. My friend instead drove me back to the condo.