A mother and her son and daughter are believed to have died after their car plunged into the flood ravaged Tweed river yesterday.
A 9-year-old girl managed to escape the vehicle before it became submerged and was able to call for help with nearby residents.
Matt Grinham, who was driving by when the car plunged into the water, tried along with two others to rescue the occupants, reports ABC.
"Even though we were diving down to the bubbles we couldn't get deep enough to touch the car," Mr Grinham told ABC.
"It was just one of those things I suppose, you just felt helpless, couldn't do anything."
Police have located the submerged car and divers are expected to begin the recovery operation this morning.
"That is a tragic event, and we're concerned it is a tragic event that will unfold over the evening and we understand that it is going to have a major impact on the family and the Tweed community," said NSW Police Commissioner Jeff Loy.
“This is about heeding the warnings of the road closures, this has been a major event and the emergency services don’t take those closures lightly.”
The girl has been treated for minor injuries and is recovering in hospital, being cared for by her family.