http://viableopposition.blogspot.ca/...ce-tactics-and-third.html

According to this there have been 27 police raids that went wrong since 1985 in which a total of 44 innocent people were killed, in the US.

This sounds like a very low number. I would guess it is much higher really. Maybe since anyone who is raided is assumed to be guilty and therefore not an innocent, the numbers are skewed in favour of the police. Same goes with reports on drone strikes. They are almost always "Al Quaida leaders". Certainly not innocent victims.