Just a question though, what actually happened. Did these people fall over the edge of one of the terraces or something. Watching a video on youtube, and there were people hanging off the edges.
Basically, the police opened a gate to ease congestion at the turnstile, which meant many people rushed into the middle two pens, leaving the pens either side, not full at all. As the people coming in tried to get a view, they weren't aware what was happening at the front. The mass of people pushed the ones at the front towards the perimeter fencing, leaving them unable to breath. The video you've seen with the people hanging off the edges will most probably be the people trying to escape by climbing over the fence.
No matter whats been said by a lot of parties since that day, it must be remembered, especially today, that those were 96 football fans, who were looking forward to a day out to support their team, cut cruelly short. It should never happen again.