After the worst flooding in living memory dumped more than a metre of rain on the northern Australian city of Townsville in seven days and destroyed an estimated 20,000 homes, residents also had another threat to contend with: crocodiles swimming down suburban streets.

At least three crocodiles were sighted in the coastal city 2,000 kilometres north of Sydney over the weekend: a three-metre crocodile spotted by emergency services and a freshwater crocodile seen climbing a tree to escape floodwaters.

A wildlife expert said the crocodiles pose a threat to people moving around the flooded city by foot or in small boats. “Crocodiles are dangerous at any time but during floods they're even more dangerous because of the lack of food,” said Gaye Lovell of Northern Queensland Wildlife Care, a volunteer-based animal rescue group in Townsville.

“The water is too deep and running too fast for them to catch anything to eat and they exhaust themselves trying. You wouldn't want to be anywhere near one them. Keep as far a distance as possible.”

Police in Townsville also issued a warning on Monday after receiving several reports of children playing in flood waters on Palm Island, a nearby island home to a community of indigenous Australians.

“Playing in flood waters is extremely dangerous, not just because of the unpredictable nature of the water itself, but also because what may lie beneath the surface,” police said in a statement. “Crocodiles have been reported in flood waters in parts of Townsville, and there can also be snakes and other wildlife present.”