After their American Idol hour was unforgivably interrupted by the San Francisco Police Department making an announcement last night, a reader writes to SFist asking:

At about 8:55pm tonight, my viewing of American Idol was disrupted by the SFPD making an announcement in the middle of our street that there will be several rounds of LIVE AMMUNITION fired in the next few minutes as they test a new gun fire detection system. I live in Silver Terrace on a decidedly working class, residential street with a lot of families with little kids. Has anyone heard about this new gun fire detection system? Or why the SFPD chose about 9pm on a Thursday night to test it?

Word is that it's all a part of a curious new technology system the police department is using that will "relay gunshot locations directly to patrol cars." The wireless sensors dotting the Bayview district will be able to pinpoint not only the location of gunfire, but the type of gun as well. Fancy, indeed. The system will cost the city a cool $400,000, and will be put to use in the Western Addition come April.