About 5,000 crocodiles lived on the farm. They are reared in Vietnam for their skin and meat.
Forest rangers, soldiers and militiamen have been searching for the creatures since they were washed away from the farm, apparently into a nearby stream.
Local official Nguyen Ngoc Hoa told the BBC how people had rushed to the scene in the hope of catching the animals and earning a reward.
"One would be paid 100,000 dong ($6; £3) for one baby crocodile, and 20,000 dong for 1kg [2.2lb] of the grown-up creature," he said.