Complex sentence: However, the proccess was, once again, interrupted by a massive fire that ended up destroying the entire studio where only the Zwijsen's musical score survived but the fire permanently marked the end of the Frijters' filmmaking career.
Split into simpler sentences: However, the proccess was, once again, interrupted by a massive fire that destroyed the entire studio. Only the Zwijsen's musical score survived but the fire permanently marked the end of the Frijters' filmmaking career.