Reasons behind looting during disasters
In many countries, even in Western democracies that otherwise ban the death penalty, extraordinary measures may be taken against looters, during times of crisis. Looters may be summarily shot by the police, army, or property owners. Extraordinary measures, combined with an impressive show of force, help to discourage looting and to disperse crowds that would otherwise find a normal show of force non-threatening. This is also common police practice in discouraging potential riots, which are often associated with looting, from escalating.
The shooting of looters may also prevent further damage to the economy. One perspective is that this also shows the relative value of economy vs. "human life" in some societies.

Measures against looting

Following the death of Valentinian III in 455, the Vandals invaded and extensively looted the city of Rome.
In 1664 the Maratha leader Shivaji sacked and looted Surat. Surat was under sack for nearly three weeks, in which the army looted all possible wealth from Mughal and Portuguese trading centers.
During the American Civil War, the New York Draft Riots (July 13-17, 1863) began as protests against President Abraham Lincoln's Enrollment Act of Conscription drafting men to fight in the ongoing war. Considered by some to be the worst civil unrest in American history, the riots included 50,000 participants and lasted several days, claiming hundreds of lives and destroying millions of dollars in property. The violent demonstration could not be contained by the civil police force, and required the intervention of regiments of the New York State Militia, who marched back to New York from the battlefield of Gettysburg, to restore civil order.
During World War II, both Nazi Germany and the Empire of Japan engaged in massive and systematic looting of valuables worth tens of billions of dollars. See:

• Nazi plunder
  Yamashita's gold
  In 1992, during the Rodney King riots, widespread looting occurred in Los Angeles, California. Some store owners guarded their stores with personal firearms.
  During the Asian Financial Crisis in 1997-98, lootings occurred in many parts of Indonesia. Looting around the world
  Trophy Art Bibliography
  
  Political and media controversy about looting
  
  Amber Room
  Looting (gaming)
  Nazi Plunder
  Pirate loot problem
  Ramraiding
  Robbery