Pilot and trainee fighting for life after light plane crash in Melbourne

A pilot and learner pilot are in a critical condition after the light plane they were flying crashed during a training session in Melbourne.

Crews were called to Pound Road in Clyde North just after 10.30am after witnesses reported seeing smoke come from the plane.

Witnesses said it appeared the pilot was looking for a place to land, before signalling a mayday call and crashing into a paddock.

Firefighters had to cut the pair out of the wreckage, with one of the men, aged in his 20s, trapped for hours. He was eventually freed, suffering serious neck, chest and back injuries, and was flown to The Alfred Hospital.

The other man was airlifted to the Royal Melbourne Hospital in a critical condition.

Both men remain in a critical condition this evening.

The Bristol single-engine aircraft was operated out of Moorabbin by Learn to Fly Melbourne.

9NEWS has contacted the company for comment but they have declined.

Civil Aviation Safety Authority spokesman Peter Gibson also confirmed the two-seater plane was on a training flight when it crashed.

"It was on a dual training flight with an instructor and a student on board," Mr Gibson said.

Investigations into what caused the crash are ongoing.