Complex sentence: A scheduled, unannounced test of the system had been planned for that day, however, "instead of running a test of the emergency alert system, midday television viewers and radio listeners were told that the state was being evacuated".
Split into simpler sentences: A scheduled, unannounced test of the system had been planned for that day. However, "instead of running a test of the emergency alert system, midday television viewers and radio listeners were told that the state was being evacuated".