Sounds politically based. Very fishy to reduce the security for this volatile match. Result lots of knifes. Nothing to do with football by the sounds of it.
Looking at the BBC site absolutely no recollection of this :
Oct 82: More than 300 reportedly killed in a stampede on a narrow, icy staircase at a Spartak-Haarlem match in Moscow
Awful reports on the radio. Fans trying to protect players and being stabbed and beaten to death on the pitch and in the changing rooms. Sounds like this was a top flight game, also reporting spread to another game.
Rumours may be reprisals from club having links to Police protests. Sounds really shocking.