One man is in a critical condition and another has serious head injuries after a light plane crash near Stawell, in Victoria's west.
Police said both men's injuries were life threatening.
The plane crashed at Black Range about 12:45pm.
Witness Grant Harrison told the ABC he saw the plane falling and spinning before it disappeared behind trees.
"It was in a flat spin. Instead of flying forwards it was just falling like a leaf and spinning, but he just didn't come back up again," he said.
Ambulance Victoria said paramedics treated the two men — a 28-year-old from Sydney and a 40-year-old from Melbourne's Altona Meadows — at the scene before flying them to hospital.
A map on the Emergency Management Victoria website placed the crash just east of the Stawell airport.
"The plane has come down in a fairly open location, surrounded by paddocks," Sergeant Pete Young told ABC Radio's Statewide Drive program.
"He's picked a location fairly well to come down.
"It's come down from a fairly good height."
He believed the two men were a trainee pilot and a pilot, though could not confirm they were on a training flight.
Victoria Police said the Australian Transport Safety Bureau (ATSB) was notified of the incident and the cause was being investigated.
According to the Civil Aviation Safety Authority (CASA), the single-engine Bristell S-LSA plane was registered with Soar Aviation, a flight training school based in Moorabbin in Melbourne's south-east.
The company posted on Facebook that the incident "has activated a comprehensive emergency response, which involves grounding all our fleet across all bases".
"Soar Aviation and emergency response teams have incident response management and procedures in place in the event of an incident of this nature.
"Soar Aviation's priority is the safety and security of our employees, students, visitors, and those involved in the incident."
Sergeant Young said the plane had left from Moorabbin, though its destination was unknown.
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