Who ordered the WH usher to have the alarm turned down/off? What authority do they have?
The Usher is responsible for the day-to-day running of the White House and its staff. He/she is not responsible for the Secret Service, and when the Usher asked them to turn the alarm off then the correct response should have been 'no'. But It's pretty clear that the Secret Service has gotten pretty lax over the last few decades since Reagan was shot.