[KC native]

And just because officers killed doesn't give all of the picture, here is assaults on police officers (2011 data from the FBI).

Overview
In 2011, the FBI collected assault data from 11,944 law enforcement agencies that employed 535,651 officers. These officers provided service to more than 251 million persons, or 80.6 percent of the nation’s population. (Based on Table 65.)
Law enforcement agencies reported that 54,774 officers were assaulted while performing their duties in 2011.
The rate of officer assaults in 2011 was 10.2 per 100 sworn officers.
More information about these topics is provided in Tables 65, 66, 70, and 71.

Injuries

26.6 percent of the officers assaulted sustained injuries.
28.5 percent of the officers who were attacked with personal weapons (e.g., hands, fists, or feet) suffered injuries.
15.7 percent of the officers who were assaulted with knives or other cutting instruments were injured.
9.4 percent of officers who were attacked with firearms were injured.
22.3 percent of officers who were attacked with other dangerous weapons were injured.

Times of incidents

For the thirteenth consecutive year, the largest percentage of assaults on officers (15.3 percent) happened from 12:01 a.m. to 2 a.m.
The smallest percentage of assaults on officers (2.6 percent) occurred between 6:01 a.m. and 8 a.m.

Circumstances
Of all officers who were assaulted in 2011:

33.3 percent were responding to disturbance calls (family quarrels, bar fights, etc.).
14.7 percent of the officers assaulted were attempting other arrests.
12.6 percent of the officers assaulted were handling or transporting prisoners.

Clearances
Law enforcement agencies can clear offenses by arrest or exceptional means (i.e., when law enforcement can identify the perpetrator, but are unable to make an arrest due to circumstances beyond their control, such as the death or suicide of the subject).

In 2011, law enforcement agencies cleared 91.3 percent of the 54,774 reported assaults on law enforcement officers.
By type of circumstance, agencies cleared the greatest percentage of assaults (93.0 percent) on officers during robberies in progress/pursuing robbery suspects.

Assignments

63.8 percent of the officers who were assaulted were assigned to 1-officer vehicle patrols.
17.0 percent of the officers who were assaulted were assigned to 2-officer vehicle patrols.
4.6 percent of officers who were assaulted were assigned to detective duties or special assignments.
14.5 percent of officers were assigned to other duties when they were assaulted in the line of duty.

Weapons
In 2011, 79.9 percent of officers who were assaulted in the line of duty were attacked with personal weapons (e.g., hands, fists, or feet).

14.3 percent of the officers were assaulted with other dangerous weapons.
4.0 percent of the officers were assaulted with firearms.
1.8 percent of the officers were assaulted with knives or other cutting instruments.