As swirling floodwaters threatened to pull her and her 7-year-old son Darcy under, Jane Sheahan managed to hand him to safety before vanishing into the torrent.
Her body was found last night near a bridge in the central Queensland town of Roma as residents turned to the task of cleaning up.
Sheahan had been missing since Friday afternoon when she drove her car into a flooded road.
"Save my boy" were the last words she spoke before she was swept away, the Sunday Mail reported.
At the time of the tragedy she had been helping neighbours to transport sandbags.
"Onlookers waved at her frantically to try and get her to stop," one witness told the Sunday Mail. But her car was swept off the roadway. Sheahan is the first victim of these Queensland floods.
Floodwaters were receding in Mitchell and Roma, but last night mandatory evacuations were declared for St George as it braced for a record flood to hit.
Upstream, rivers were rising quickly and the Balonne River was expected to peak in St George at 14-15m.The devastating flood that tore through the town in 2010 peaked at 13.5m.
Residents were last night being told to leave town along the Moonie Highway before it was cut by floodwaters.
Air evacuation to Brisbane was being organised so evacuations could proceed after the highway closes.
Queensland Premier Anna Bligh urged residents to follow directions.
An air force C-130 Hercules transport was sent to evacuate hospital patients from St George Base Hospital to hospitals in Brisbane and the Gold Coast. Buses were also evacuating St George residents without their own transport to nearby Dalby - where an evacuation centre was set up.
Brisbane Mayor Graham Quirk told ABC Radio the city's RNA Showgrounds would be set up as a recovery centre for St George residents.
"So we're ready. We're on standby and should the need arise, we'll be ready to whip into action," Quirk said.
Prime Minister Julia Gillard said the Hercules joined eight Defence Force helicopters already assisting flood-relief efforts in southeast Queensland.
Maranoa Regional Council said yesterday that 396 buildings so far had had preliminary flood damage assessment in Mitchell, and 281 had been affected by water inundation.
Food and medical supplies were still being airlifted into Mitchell and Roma, with 290 evacuees remaining in the Mitchell evacuation centre and 48 in Roma last night.