Complex sentence: The Government of Ireland was not informed for the duration of that three-day period and when it was a major bomb alert occurred on the busy thoroughfare of Dorset Street in Dublin, leading to the man being arrested, and later released without charge.
Split into simpler sentences: The Government of Ireland was not informed for the duration of that three-day period. When it was, a major bomb alert occurred on the busy thoroughfare of Dorset Street in Dublin, leading to the man being arrested, and later released without charge.