Complex sentence: The first riots associated with Shakhtar fans held on 20 September 1959 in the match against CSKA Moscow, when several dozen Shakhtar supporters ran onto the field, and as a result the match was frustrated.
Split into simpler sentences: The first riots associated with Shakhtar fans held on 20 September 1959 in the match against CSKA Moscow. Then on the field ran several dozen Shakhtar supporters and as a result the match was frustrated.