For those not in the business…

the tones you hear at he end of the video are emergency radio tones for radio silence…

and the announcement of the officers shield numbers have gone “off duty”…

it’s done as a tribute for those officers/staff who are on duty and not in attendance as a way of honoring their fallen comrades who are here to “protect and serve”.

http://www.theledger.com/static/flash_video/20061004_matt_williams/index.html