Cops are always leaving their cars running with all sorts of ordnance inside. I see it all the time.
Me too...and I can guarantee you that if I left my car running, they would give me a ticket. We just had a 90-100 MPH car chase in a 40 MPH zone through San Antonio a few days ago when a perp stole a cop car. It scared the crap out of me as I was right at the intersection where he was heading and there were so many speeding cops in the area that everyone was panicking, not knowing which way to go to avoid them.