Complex sentence: King was in the room directly beneath Martin's at the Lorraine Hotel when the gun blast went off, and when he saw his brother lying mortally wounded, he had to be restrained by others due to the shock and overwhelming emotion he was experiencing.
Split into simpler sentences: King was in the room directly beneath Martin's at the Lorraine Hotel when the gun blast went off. When he saw his brother lying mortally wounded, he had to be restrained by others due to the shock and overwhelming emotion he was experiencing.