I was once chatting to the accountant at a company I was visiting, a Liverpool season ticket holder, who had been at that match, but had been in the seats ABOVE the terracing, and had witnessed it all. This was only 3 or 4 months after it happened, and he was still traumatised by the events that had taken place.
Interestingly, he told me that the previous year, when Livepool had been there for another semi, he had been standing in that central area. About 5 minutes into the match there was a surge forward and a lot of supporters were crushed against the barriers, which he was standing in front of. He vowed then that if they ever went to Hiilsborough again, he would go in the seats. Apparently , a lot of supporters were allowed in to the ground to alleviate the queueing outside! Fortunately, no one was badly hurt, but, obviously, lessons on crowd control were not learned, leading to those tragic events 12 months later.