Girl dead, men injured after plane crash

A young girl has died and two men have survived a plane crash into a northern NSW river believed to have happened after their aircraft hit power lines.

The pilot, a 50-year-old man who suffered only minor injuries, freed himself from the wreckage and called authorities seeking help for his two passengers following the crash southwest of Casino on Saturday morning, police said.

They were able to save a 39-year-old male passenger who was taken to Lismore Base Hospital by helicopter, where he remains in a serious condition.

A 12-year-old girl died at the scene.

"It's believed the aircraft hit power lines and then crashed into a nearby river," police said.

A crime scene has been established and a report will be prepared for the coroner.

The Australian Transportation Safety Bureau will investigate the cause of the crash.