A trench has collapsed on a man on a worksite in Terrey Hills.
At approximately 12.45pm this afternoon, paramedics were called to the site following reports that a man in his 40s was injured.
The man has sustained suspected pelvic, chest and neck injuries.
According to NSW Ambulance, six units responded to the incident, including the CareFlight helicopter.
The man was initially pinned from his chest down by rocks and soil.
His workmates managed to free him.
Inspector Andrew Rienitis said that it was lucky that the colleagues had acted quickly,
"We were on the scene within minutes but the patient had luckily been retrieved by his colleagues," he said.
"The chopper has landed on a nearby oval ready to transport the 45-year-old man.
"At the end of the day we have done everything that we can, but it's the quick thinking actions of his work mates that needs to be commended."
The patient is in a serious condition and paramedics are currently treating the man at the scene.