According to this site 105 cops killed in line of duty in 2013.
Only 30 of those were shot by attackers. 25 died in car accidents, some of which might have been in chases, although they have a separate category for vehicular pursuit (4 dead).
10 had heart attacks. They appear to include any and all cop deaths on duty.
Police work is not, statistically, a particularly dangerous line of work. In fact, it isn’t in the top 10.
http://www.odmp.org/search/year?year=2013
;-)
BLS says Logging is the most dangerous job for 2013, with 91.3 fatalities per 100,000 workers. Policemen, Firemen and EMS are not even in the top 10.