It's been a deadly, tragic week for law enforcement in the United States, as at least five officers have been shot and killed in the last four days.

All of the shootings occurred in the line of duty.

CNN:

In four days, five officers were killed in the line of duty in shootings around the country, more than doubling the number of officers who have died by gunfire so far this year.

A Colorado sheriff's deputy died after being shot Monday; two sheriff's deputies were killed Wednesday in Maryland; a police officer in Georgia is dead after gunfire broke out Thursday while he and other officers were serving a warrant; and a police officer shot Wednesday night in North Dakota did not survive, authorities say.

Before these deaths were reported, the National Law Enforcement Officers Memorial Fund said at least three other U.S. law enforcement officers had died from gunfire in the line of duty this year. Adding the totals together, that would make at least eight since January 1.

One officer was shot to death during the same period last year, and at least 42 were fatally shot in 2015 -- a rate of less than one per week -- according to the group.

At least 124 officers died in the line of duty last year -- more than two per week -- from all causes, the group said.

The place names where the officers served and died offer a slice of Americana; Abingdon, Maryland; Fargo, North Dakota; Grand Junction, Colorado; and Riverdale, Georgia. 

It doesn't matter where you serve if you're a law enforcement officer; the danger remains.  All of those men left home on the mornings of their deaths, knowing they might not return that night but determined to serve and protect anyway.

Their sacrifice defines courage, honor, and duty.