Right or wrong, angry people, being forced to leave their homes, are taking anything that that can from homes. AC unite, hot water heaters, central vac units, etc.
If you suspect this is happening, your agent should be aggressively involved in taking measures to protect your interests. At the very least, it should be brought to the attention of the listing agent. If this is a short sale or pre-foreclosure the bank should be notified as well.