My best advice would be to type it into YouTube.
Too many fans were allowed into pens at Hillsborough and many were crushed and 96 were killed. It was an overcrowding situation. Fans rushed onto the pitch early in the match to avoid the crush. The match was a 1989 FA Cup Semifinal between Liverpool and Nottingham Forrest held at Hillsborough. A report came out this week (or maybe last week) that stated that the Liverpool fans were not the cause of the disaster.
ETA: Or, better yet, just read Beast's post.
This post was edited on 9/24 at 12:54 am