A Malaysian and a Taiwanese who were driving separately to work on the same corn farm in Queensland, died when their cars plunged into a swollen river in Lockyer Valley, early Sunday morning.

Andrew Leong, 34, from Subang Jaya, Selangor and Pan Yukun, 25, from Taiwan both drove into the Sandy Creek near Gatton, minutes before it peaked, in a twin tragedy that has increased to six, the death toll in the Queensland flood crisis, The Australian newspaper reported.

Leong's body was found inside his car after it was pulled out from Sandy Creek.

Queensland Police Inspector Richard Kroon said there was no way of knowing whether one car was tailing the other, or whether the vehicles entered the creek at different times, their drivers failing to recognise the danger, until it was too late.

Kroon told the newspaper the causeway was a notorious flash-flood point, well known to locals, but probably not to the foreign workers who descended on the area to pick fruits and vegetables.

"The water flows through there quite rapidly," he said. "I guess that would be a reasonable assumption, that people who would be unfamiliar with the area...it could be quite a surprise to them.

"On the weekend, the Lockyer Valley had been drenched with torrential rain, reminding locals of the deadly deluge that swept through the region in January 2011, killing 19 people," he said.

In the 10 hours before Leong and Yukun embarked on their separate journeys, Sandy Creek, normally a quiet and calm trickle of a stream, surged to a violent peak of 3.2m.