When heavy rains begin to pelt a flood-prone neighborhood along Puerto Rico's north coast, people start sharpening their knives and preparing their lassoes.

The floods herald the arrival of caimans, a close relative of the alligator, whose population has exploded in and around the lagoon next to Los Naranjos neighborhood in the coastal city of Vega Baja.

The scaly reptiles have been spotted prowling around schools and crawling into flooded yards after rains, causing both widespread panic and curiosity in the community.