Complex sentence: Croatian hooligans are also notorious for staging large illegal pyroshows at stadiumsrge incident occurred in 2003 in which signal flares and smoke bombs are hurled into the pitch causing postponement or cancellation of the match.
Split into simpler sentences: Croatian hooligans are also notorious for staging large illegal pyroshows at stadiums. An incident occurred in 2003, in which signal flares and smoke bombs were hurled onto the pitch causing postponement or cancellation of the match.