An Australian tour guide plunged into a croc-infested swamp in a desperate bid to save his five-year-old son snatched by a 10-foot-long crocodile.

Steve Doble of Queensland, who owns Daintree Rainforest Rivertrain, flung himself into the waist-deep floodwaters Saturday only to find that his youngest boy had vanished.

He was alerted by the screams of his older son Ryan, 7, who had to be treated for shock after witnessing the attack.

Jeremy Doble, 5, is missing and feared dead after he was taken by the crocodile in the swamp behind his family home.

Locals said the "sweet, gentle-natured" child and his older brother were playing on a boogie board as their father fixed a broken boardwalk nearby, The Courier-Mail reported.

The Doble family was too upset to speak publicly about their ordeal Saturday.

"It is just devastating," said long-time local Col Patterson, 44, whose family built and sold the tourist property to the family five years ago.

"Dad jumped in after him, but it was too late," Patterson said. "His older brother saw it all and will, no doubt, be haunted by that image."

Click here for more on this story from News.com.au.