But there actually are a rather large number of attacks on police at police stations
https://www.usatoday.com/story/news/nation-now/2016/10/14/shootings-indianapolis-police-stations/92051478/
http://wjla.com/news/local/police-officer-shot-in-maryland-possible-active-shooters
https://www.washingtonpost.com/local/public-safety/police-take-third-brother-into-custody-in-shooting-of-police-officer/2016/03/14/74b97f36-e9e6-11e5-b0fd-073d5930a7b7_story.html?utm_term=.bbffb86c00d3
https://www.cnn.com/2016/07/10/us/san-antonio-police-headquarters-shooting/index.html
http://www.policemag.com/videos/channel/swat/2017/03/suspect-opens-fire-on-deputies-at-ca-sheriff-s-station.aspx