According to another Associated Press report, "A giant new Wal-Mart in New Orleans was looted, and the entire gun collection was taken, The Times-Picayune newspaper reported. 'There are gangs of armed men in the city moving around the city,' said Ebbert, the city's homeland security chief."
Why does this occur?
Gov. Blanco "acknowledged that looting was a severe problem but said that officials had to focus on survivors. 'We don't like looters one bit, but first and foremost is search and rescue.'" Private property is not being adequately protected by the owners or by law enforcement because the cost of protecting it would come at the expense of human life. When we have to allocate scarce resources, we try to do so in the most effective manner, putting the resource to its best use. This means there is a tradeoff. We can't protect everyone and everything, so we deal with the cost of not protecting things that we'd like to.
When property rights are not enforced, people do not respect those rights (aside from any moral foundation they personally hold). The effect that we observe is as though property rights do not exist. If property rights do not exist, anything is for the taking and there is no price system for exchange. Instead, those who are able to obtain items and keep them by force become the 'owners.' Thus, we can expect the use of violence to become the primary means of acquiring scarce goods and this is exactly what we see in the aftermath of Hurricane Katrina.