killing field

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A site of large-scale, often systematic killing, especially a site of prolonged genocidal murder.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun the field of fire of a machine gun or artillery
• noun a place of mass slaughter; especially the Killing Fields of Cambodia

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun (usually plural) an area where many people have died (usually by massacre or genocide during war or violent civil disturbance)